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  • Angiosperms  (77)
  • 36.40  (59)
  • Springer  (136)
  • American Chemical Society
  • American Meteorological Society
  • 1995-1999
  • 1990-1994  (136)
  • 1991  (136)
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Keywords
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  • Springer  (136)
  • American Chemical Society
  • American Meteorological Society
Years
  • 1995-1999
  • 1990-1994  (136)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Coherent raman spectroscopy of nitrogen molecules and clusters in supersonic jets (1991)
    Springer
    Applied physics 52 (1991), S. 84-89 
    Details
    ISSN: 1432-0649
    Keywords: 36.40 ; 42.65 ; 47.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Coherent Stokes and anti-Stokes Raman scattering CSRS and CARS have been employed to study the spectroscopy of nitrogen molecules and clusters in the expansion of a supersonic jet. In the vibrational spectrum, at strong stagnation conditions, an intense redshifted peak is observed which can be assigned to the intramolecular vibrations in large N2 clusters having adopted the β-phase structure. Another weak feature is assigned to nitrogen clusters in the α-phase. In the rotational region of the spectrum only monomer features have been observed. The failing to observe librational motions is consistent with the finding that the nitrogen clusters are predominantly in the orientationally unordered β-phase. The low rotational temperature suggests supercooling of the β-phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357660
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  • 2
    Electronic Resource
    Electronic Resource
    Laser-fluorescence diagnostics for condensation in laser-ablated copper plasmas (1991)
    Springer
    Applied physics 53 (1991), S. 353-361 
    Details
    ISSN: 1432-0649
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We are investigating the thermodynamic conditions under which condensation occurs in laser ablated copper plasma plumes. The plasma is created by XeCl excimer laser ablation (308 nm, 300 mJ/pulse) at power densities from 500–1000 MW/cm2 into backing pressures of helium in the range 0–50 torr. We use laser-induced fluorescence (LIF) to probe velocity and relative density of both atomic copper and the copper dimer molecule, Cu2, which is formed during condensation onset. At low pressure (10 mtorr), the atomic Cu velocity peaks at approximately 2×106 cm/s. Copper dimer time-of-flight data suggest that condensation onset occurs after the Cu atoms have slowed very significantly. Excitation scans of the Cu2A-X (0,0) and (1,1) bands yield a rotational and vibrational temperature in the neighborhood of 300 K for all conditions studied. Such low temperatures support the theory that Cu2 is formed under thermally and translationally cold conditions. Direct laser beam absorption is used to determine the number density of atomic copper. Typical densities attained with 5 torr of helium backing gas are 6–8×1013 cm−3. Rayleigh scattering from particulate is easily observable under conditions favorable to particulate production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331827
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  • 3
    Electronic Resource
    Electronic Resource
    Angiosperm origin and early stages of seed plant evolution deduced from rRNA sequence comparisons (1991)
    Springer
    Journal of molecular evolution 32 (1991), S. 253-261 
    Details
    ISSN: 1432-1432
    Keywords: Chloroplast 4.5S rRNA ; Cytosolic and chloroplast 5S rRNAs ; 5.8S rRNA ; 18S rRNA ; Nucleotide sequences ; Phylogenetic trees ; Angiosperms ; Gymnosperms ; Monocotyledons ; Dicotyledons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complete or partial nucleotide sequences of five different rRNA species, coded by nuclear (18S, 5.8S, and 5S) or chloroplast genomes (5S, 4.5S) from a number of seed plants were determined. Based on the sequence data, the phylogenetic dendrograms were built by two methods, maximum parsimony and compatibility. The topologies of the trees for different rRNA species are not fully congruent, but they share some common features. It may be concluded that both gymnosperms and angiosperms are monophyletic groups. The data obtained suggest that the divergence of all the main groups of extant gymnosperms occurred after the branching off of the angiosperm lineage. As the time of divergence of at least some of these gymnosperm taxa is traceable back to the early Carboniferous, it may be concluded that the genealogical splitting of gymnosperm and angiosperm lineages occurred before this event, at least 360 million years ago, i.e., much earlier than the first angiosperm fossils were dated. Ancestral forms of angiosperms ought to be searched for among Progymnospermopsida. Genealogical relationships among gymnosperm taxa cannot be deduced unambiguously on the basis of rRNA data. The only inference may be that the taxon Gnetopsida is an artificial one, andGnetum andEphedra belong to quite different lineages of gymnosperms. As to the phylogenetic position of the two Angiospermae classes, extant monocotyledons seem to be a paraphyletic group located near the root of the angiosperm branch; it emerged at the earliest stages of angiosperm evolution. We may conclude that either monocotyledonous characters arose independently more than once in different groups of ancient Magnoliales or that monocotyledonous forms rather than dicotyledonous Magnoliales were the earliest angiosperms. Judging by the rRNA trees, Magnoliales are the most ancient group among dicotyledons. The most ancient lineage among monocotyledons leads to modern Liliaceae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02342748
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  • 4
    Electronic Resource
    Electronic Resource
    Cluster emission under ion bombardment of metallic targets (1991)
    Springer
    Applied physics 52 (1991), S. 213-217 
    Details
    ISSN: 1432-0630
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Mass spectroscopic studies of the neutral particles sputtered by Ar+ ions at 8 keV from polycrystaline samples have been performed, using non-resonant laser ionization and subsequent time-of-flight mass spectroscopy. Besides sputtered atoms, also dimer and trimer contributions in the order of 10−1 to 10−2 and 10−3 to 10−4, respectively, are found in the sputtered flux. The data obtained here together with previously published data by other groups for different bombarding energies provide strong support for the validity of the recombination model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324422
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  • 5
    Electronic Resource
    Electronic Resource
    Laser-stimulated desorption of potassium atoms (1991)
    Springer
    Applied physics 52 (1991), S. 445-447 
    Details
    ISSN: 1432-0630
    Keywords: 82.65 ; 36.40 ; 73.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Desorption of K atoms by laser-excitation of surface plasmons in small K particles is reported. The desorption rate has been measured for different laser wavelengths and particle sizes. Time-of-flight measurements reveal a kinetic energy of the desorbed atoms of Ekin=0.13(3) eV. From the experimental data it is concluded that the desorption mechanism is non-thermal in nature. Comparison of the results reported here with our earlier work on Na desorption is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323657
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  • 6
    Electronic Resource
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    The developmental morphology ofIndotristicha ramosissima (Podostemaceae, Tristichoideae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 195-223 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Podostemaceae ; Tristichoideae ; Indotristicha ramosissima ; Rheophytes ; water plants ; life history ; development ; root-shoot model ; leaf-stem intermediates ; phyllotaxis ; flower structure ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The developmental morphology ofIndotristicha ramosissima, a submerged rheophyte from South India, is described. Besides creeping organs (called roots) there are branched shoots with two kinds of short-lived photosynthetic appendages: scales and compound structures (called ramuli). These ramuli may be interpreted as leaf-stem intermediates because they combine typical leaf characters (extra-axillary position, determinate growth, subtending an axillary bud) and typical stem characters (nearly radial symmetry, acropetal development with apical meristem, arrangement of the scaly subunits helical or irregular). Floral shoots arise from axillary exogenous buds along the vegetative shoots, occasionally also from endogenous buds along the roots and vegetative shoots. The uppermost scales and ramuli of each floral shoot form a cup-like structure around the base of the terminal flower.Indotristicha is thought to be primitive within theTristichoideae (Podostemaceae). Some morphogenetic switches are postulated in order to deriveIndotristicha from a putative ancestor that still showed the classical root-shoot model typical of most angiosperms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937964
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  • 7
    Electronic Resource
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    Quantitative nuclear DNA changes inEleusine (Gramineae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 225-233 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Gramineae ; Eleusine ; DNA amount ; intra- and interspecific variation ; karyotypes ; hybridisation ; polyploidy ; domestication ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2C nuclear DNA amounts were determined in 30 collections belonging to 10 species ofEleusine. About a 2.5-fold variation in genome size is evident in the genus. The 2C DNA amount in the diploid species ranged from 2.50 pg inE. verticillata to 3.35 pg inE. intermedia. In contrast, the tetraploid species showed a range from 4.95 pg inE. africana to 6.13 pg inE. floccifolia. At intraspecific level 10 collections ofE. coracana, 6 ofE. indica, 4 ofE. africana, 2 ofE. tristachya, and 2 ofE. kigeziensis did not show any significant variation. However, 2 collections ofE. floccifolia, connected with polyploidy, displayed about 90% variation. Polyploid species showed approximately double the genome size of that of their corresponding diploids. An evolutionary increase in DNA amount is evident inE. coracana during the course of its origin and domestication fromE. africana.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937965
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  • 8
    Electronic Resource
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    Polyploidy and aneuploidy inOphrys, Orchis, andAnacamptis (Orchidaceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 235-245 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Ophrys ; Orchis ; Anacamptis ; Polyploidy ; aneuploidy ; karyology ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies on chromosome numbers and karyotypes in Orchid taxa from Apulia (Italy) revealed triploid complements inOphrys tenthredinifera andOrchis italica. InO. tenthredinifera there is no significant difference between the diploid and the triploid karyotypes. The tetraploid cytotype ofAnacamptis pyramidalis forms 36 bivalents during metaphase I in embryo sac mother cells. Aneuploidy was noticed inOphrys bertolonii ×O. tarentina with chromosome numbers n = 19 and 2n = 38. There were diploid (2n = 2x = 36), tetraploid (2n = 4x = 72), hexaploid (2n = 6x = 108) and octoploid (2n = 8x = 144) cells in the ovary wall of the diploid hybridOphrys apulica ×O. bombyliflora. Evolutionary trends inOphrys andOrchis chromosomes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937966
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  • 9
    Electronic Resource
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    Pollination of four sympatric species ofAngelonia (Scrophulariaceae) by oil-collecting bees in NE. Brazil (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 153-178 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Scrophulariaceae ; Angelonia ; Anthophoridae ; Centris ; Oil flowers ; pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The manner whereby the oil-producing bisaccate flowers ofAngelonia (Scrophulariaceae) are pollinated by female oil-collecting bees is reported for the first time. Observations were made in the Caatinga formation of Pernambuco, NE. Brazil, on four synchronopatric species. These differ in sizes and structural details of the corolla, level of flower exposition, and habitat preferences. All legitimate visitors wereCentris spp. (Anthophoridae):Angelonia hirta was mainly pollinated byC. fuscata andA. pubescens byC. hyptidis; A. bisaccata andA. hookeriana shared an unidentified species. Several exomalopsine, tetrapediine and meliponid bees exploit the flowers less descriminately for oil or pollen, respectively, without regularly contacting anthers and stigma. The flowers are protandrous, and are self-incompatible except those of the annualA. pubescens. After alighting, theCentris bees introduce their front legs simultaneously into each of the pouches and start alternate collecting movements to gather the oil from the trichome elaiophores. While doing so, they are forced by projections of the corolla floor to press their head under the anthers and stigma, whereby pollen is transferred with their frons or clypeus. On account of their collector type and behaviour,C. fuscata andC. spec. are not specialized toAngelonia but may equally exploit other nonrelated taxa for oil, whereasC. hyptidis exhibits oligolecty onA. pubescens. It possesses relatively elongate forelegs with padlike collectors suitable for sweeping the lipids from the scattered glandular hairs inside the divergent spurs of its host. It is the only species that also collects pollen (by buzzing) from the oil host.A. hirta and relatives, provided with dense elaiophore carpets, are, for their part, adapted to “scraping”Centris species with typical oil collectors. Flower and bee phenologies, although largely dependent on the irregular rainfalls, are not always coincident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937962
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  • 10
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    Androecium and floral nectaries ofHarungana madagascariensis (Clusiaceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 179-194 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Clusiaceae ; Harungana madagascariensis ; Androecium ; stamenpetal complex ; floral nectaries ; floral development ; floral anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mature flower ofHarungana madagascariensis (Choisy)Poir. has an androecium of five antipetalous fascicles, consisting of four stamens each. The stamen fascicles alternate with five indented nectary scales. A SEM-study of the floral development, as well as a study of the floral anatomy was carried out to understand whether the nectariferous scales represent staminodia or are receptacular in nature and consequently whether or not the androecium ofHarungana, and theClusiaceae in general, is originally diplostemonous. The five petals originate by the splitting of petal-stamen complexes. Next the upper part of each complex differentiates basipetally in four stamens. The stamens remain fascicled and are lifted on a long stalk at maturity. Five carpel primordia are initiated united in a low ringwall. The five nectary scales appear after carpel inception and develop an external morphology reminiscent of anthers. The floral anatomy reveals an independent origin of sepal median traces and common sepal lateral traces, free petal traces, stamen fascicle traces and alternating vascular tissue which supplies the nectaries. The petal-stamen complexes are the result of a retardation in petal inception, linked with the absorption of petal tissue into the stamen primordia. The development of the stamen fascicles is discussed; it is suggested that they are of a secondary nature and do not appear as a reduction from a multistaminate androecium. The external morphology and vascular anatomy of the scales speaks in favour of a staminodial nature. The comparison with some other species of theClusiaceae gives evidence of a diplostemonous ancestry of the androecium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937963
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  • 11
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    Double fertilization inEphedra trifurca, a non-flowering seed plant: The relationship between fertilization events and the cell cycle (1991)
    Springer
    Protoplasma 165 (1991), S. 106-120 
    Details
    ISSN: 1615-6102
    Keywords: Angiosperms ; Cell cycle ; Double fertilization ; Endosperm ; Ephedra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fertilization inEphedra trifurca was examined with a combination of light and fluorescence microscopy. Developmental analysis clearly indicates that double fertilization events, similar to those described inE. nevadensis, regularly occur during the process of sexual reproduction inE. trifurca. In addition to the typical fusion of a sperm nucleus and egg nucleus, a second fertilization event occurs between the second sperm nucleus from an individual pollen tube and the ventral canal nucleus. Both of the fertilization events take place within the confines of an individual egg cell of the female gametophyte. Microspectrofluorometric data demonstrate that each nucleus involved in a sexual fusion event proceeds through the synthesis phase of the cell cycle and increases its DNA content from 1C to 2C before the process of nuclear fusion is completed. Photometric data also confirm that the product of the second fertilization event is equal in DNA content (4C) to the zygotic nucleus derived from the first fertilization event, and is prepared to enter into mitosis as a fully functional diploid nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322281
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  • 12
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    Distribution of naturally occurring quinones (1991)
    Springer
    Pharmacy world & science 13 (1991), S. 70-73 
    Details
    ISSN: 1573-739X
    Keywords: Algae ; Angiosperms ; Arthropods ; Bacteria ; Fungi ; Lichens ; Marine animals ; Quinones, naturally occurring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Angiosperms, fungi (including lichens), and bacteria are the main sources of natural quinones. Small numbers are present in algae, ferns, conifers, sponges, echinoderms, other marine animals, and arthropods. In angiosperms quinones have some chemotaxonomic value at the genus and family level but more surveys are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974983
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  • 13
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    Experimental documentation of natural hybridization inCactaceae: Origin of Lloyd's Hedgehog Cactus,Echinocereus ×lloydii (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 107-122 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cactaceae ; Echinocereus ; Natural hybridization ; systematics ; dioecy ; flavonoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The origin ofEchinocereus ×lloydii Britt. & Rose, pro sp. (Lloyd's Hedgehog Cactus) was investigated using comparative morphology, cytology, biochemistry, and particularly, artificial hybridization. Numerous artificial crosses between the putative parentsE. coccineus Engelm. (a species of claret-up cactus) andE. dasyacanthus Engelm. (Texas Rainbow Cactus) were successful, resulting in the production of hundreds of seeds with hybrid embryos. The F1 hybrid progeny (i.e., syntheticE. ×lloydii) grew to sexual maturity in about four and one-half years, whereupon successful backcrosses and F2 generation hybrids were also obtained. The known F1 hybrids closely approximated naturalE. ×lloydii. The fertility of these syntheticE. ×lloydii was high, like their natural counterparts. The populations ofE. ×lloydii in Pecos County, Texas are inferred to have originated as the result of natural interspecific hybridization. It is assumed thatE. ×lloydii or similar plants may arise wherever the parental taxa grow sympatrically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937985
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  • 14
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    Allozyme diversity and systematics inAnnonaceae—a pilot project (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 125-134 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Annonaceae ; Allozymes ; genetic variation ; systematics ; evolution in tropical woody plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five species ofAnnona and one species fromArtabotrys, Cananga, Polyalthia, andRollinia were investigated in regard to 11 different allozyme loci. Preliminary studies on small population samples ofAnnona suggest genetic uniformity in three species and variability within and between populations in two other species. The allotetraploid origin ofA. glabra is clearly shown by its hybrid enzyme bands. The genetic distance between fiveAnnona species partly corresponds with their morphological relationships; onlyA. muricata appears more separated than is suggested by morphology. A comparison of the five genera demonstrates close relationship betweenAnnona andRollinia. Two enzyme loci are identical within all taxa investigated and possibly may serve as a genetic marker for the family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937960
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  • 15
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    Globba unifolia andG. corneri stat. et nom. nov. (Zingiberaceae; Peninsular Malaysia) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 1-4 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Zingiberaceae ; Globba ; Taxonomy ; Flora of Malesia and Malaysia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on personal collections ofGlobba unifolia Ridl. andG. unifolia var.sessiliflora Holtt., the latter is recognized as a distinct species. As the nameG. sessiliflora is already occupied, the nomen novumG. corneri is proposed in honour of Prof. DrE. J. H. Corner, who was the first collector of the plant.
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    URL: http://dx.doi.org/10.1007/BF00937689
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  • 16
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    The effect of crossing distances and population subdivision on floral morphology inScleranthus annuus (Caryophyllaceae), a selfing annual (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 5-16 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Caryophyllaceae ; Scleranthus ; Floral morphology ; within-population crosses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I used a discontinuous population ofScleranthus annuus (Caryophyllaceae) to study the effect of crossing distances on flower morphology of the progeny. Four types of progeny were produced by artificial selfing, crossing with pollen-donors from the same patch in the population, crossing with pollen from donors from other patches in the population and inter-population crosses. The size of gynoecium parts and 12 sepal characters in this petal-lacking species were significantly influenced by the type of cross and the patch in the population from where the seed-parents originated. All comparisons of progeny types except selfed vs progeny produced by within-patch crosses were significantly separated from each other, while all four seed-parent patches used were significantly separated in a multidimensional space.
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    URL: http://dx.doi.org/10.1007/BF00937690
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  • 17
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    Pollination biology ofNierembergia (Solanaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 17-35 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Solanaceae ; Nierembergia ; Tapinotaspis ; Centris ; Lanthanomelissa ; Paratetrapedia ; Pollination biology ; oil-flowers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A morphological and anatomical description of the floral syndrome ofNierembergia is given, including a survey of the presence of elaiophores in most of its species, chromatography of the floral oils and observations on the pollinator behaviour. The principal pollinators areTapinotaspis spp. includingT. chalybaea which is endowed with oil collectors on the middle legs. Other exomalopsines (Lanthanomelissa andParatetrapedia) and centridines (Centris) also visitNierembergia for pollen and oil. Based on these observations and on a morphological study of the fertile parts, different pollination modes are recognized and the biogeography and evolution of the genus is discussed.
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    URL: http://dx.doi.org/10.1007/BF00937691
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  • 18
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    Medicago truncatula f.laxicycla (Leguminosae), a new taxon with loose fruit coiling promoting rapid germination of the fruit-retained seeds (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 37-46 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Medicago truncatula f.laxicycla ; M. laxispira ; Evolution ; adaptation ; seed germination ; chromosome number ; Flora of Libya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Medicago truncatula is a member ofMedicago sect.Spirocarpos, in which all 34 species have coiled fruit, usually tightly coiled, that permanently retain the seeds. A variant ofM. truncatula from Libya is unique for the species in possessing very loosely coiled fruits, and is here recognized as a new forma,M. truncatula f.laxicycla E. Small. In germination tests of a number of species ofMedicago, the unusual Libyan variant proved to be the only one in which rapid and simultaneous germination of most of the seeds occurred while still within a fruit. The loose coiling of the fruit of the Libyan variety appears to facilitate water entry and seedling escape. Its rapid germination might adapt it to respond quickly to intermittently available moisture, but at the cost of abandoning the strategy of intermittent germination adopted by other populations ofMedicago sect.Spirocarpos.
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    URL: http://dx.doi.org/10.1007/BF00937692
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  • 19
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    Subgroups in theHordeum patagonicum complex (Poaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 47-66 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Hordeum patagonicum complex ; barley ; Classification ; numerical methods ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seeds of theHordeum patagonicum complex were collected from the field and grown in the greenhouse. The aim was to take a sample of members of the complex, and on the basis of the phenotypic similarities in some morphological and physiological characters, determine whether distinct groups exist. When cluster analyses, to generate hypotheses, and orthodox statistical procedures, for hypotheses obtained a priori, were applied to the reproductive morphology, germination and flowering patterns, onlyH. patagonicum subsp.magellanicum, out of the five recognized taxa, could be distinguished consistently. The remaining four taxa, which overlapped considerably, could be re-formed into three groups whose centroids were different but whose ranges of variation were not distinct from each other. We conclude that the highly cross-compatible members of theH. patagonicum complex, first defined as species and later redefined as subspecies are probably no more than biotypes.
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    URL: http://dx.doi.org/10.1007/BF00937693
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    Genome analysis ofElymus angulatus andE. patagonicus (Poaceae) and their hybrids with N. and S. AmericanHordeum spp. (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 75-82 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Triticeae ; Elymus ; Hordeum ; Intergeneric hybrids ; genome analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The results of genome analysis of five hybrids, viz.Elymus patagonicus ×Hordeum procerum, E. patagonicus ×H. tetraploidum, E. angulatus ×H. jubatum, E. angulatus ×H. lechleri, andE. angulatus ×H. parodii, are reported. The genomic constitution ofHordeum tetraploidum andH. jubatum is best given as H1H1H2H2, ofH. lechleri andH. parodii as H1H1H2H2H4H4, ofH. procerum as H1H1H2H2H3H3, and ofElymus patagonicus andE. angulatus as SSH1H1H2H2.
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    Electrophoretic study and genetic affinity in theCampanula elatines andC. fragilis (Campanulaceae) rock-plants group from Italy and W. Jugoslavia (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 67-73 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Campanulaceae ; Campanula isophylla ; C. elatines ; C. elatinoides ; C. fragilis subsp.fragilis and subsp.cavolinii ; C. garganica ; C. fenestrellata subsp.istriaca ; C. portenschlagiana ; Allozyme variation ; heterozygosity ; Flora of Italy and W. Jugoslavia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variability and genetic divergence of 11 field populations of seven species of theCampanula elatines andC. fragilis rock-plants group from the Mediterranean and pre-Alpine areas have been studied by starch-gel electrophoretic techniques.Campanula isophylla, C. elatines, C. elatinoides, C. fragilis subsp.fragilis and subs.cavolinii, C. garganica were collected in Italy, whilstC. fenestrellata subsp.istriaca andC. portenschlagiana came from W. Jugoslavia. Twelve enzymatic loci for each population were genetically analysed: PGI-1 and 2, PGM-2, IDH-1 and -2, SKDH, ME, ADH, GOT-2, MPI-1 and -2, SOD-1. The genetic distances among the above mentioned entities have been calculated by Nei's index and depicted in a dendrogram.
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    Morphology and distribution of trichomes in Italian species ofTeucrium sect.Chamaedrys (Labiatae) — a taxonomical evaluation (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 83-91 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Labiatae ; Teucrium sect.Chamaedrys ; Taxonomy ; trichomes ; Flora of Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Micromorphology and distribution of trichomes (both secretory and not) in different parts of plants of the five Italian species belonging toTeucrium sect.Chamaedrys have been studied. These characters neatly evidence the differences between the taxa considered; of particular interest are the observations concerning the dense coverage of peltate hairs on the abaxial face of the leaves ofT. flavum subsp.glaucum and the characters contributing to a better identification ofT. marum andT. subspinosum. The importance of the calyx indumentum as distinctive taxonomical character of the genusTeucrium is confirmed, stressing at the same time the necessity of completing the observations at micromorphological level.
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    Pollinator limitation and position dependent fruit set in the high Andean orchidMyrosmodes cochleare (Orchidaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 93-101 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Myrosmodes cochleare ; Pollination ; breeding system ; Andes of Venezuela
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Myrosmodes cochleare is a terrestrial orchid restricted to high elevations of the northern Andes. It is self-compatible but not autogamous. Flowering begins at the apex of the inflorescence, but flower size increases steadily towards the base. Fruit set of selfed flowers was found to increase significantly from the apex to the base of the inflorescence. Open-pollinated fruit set was significantly lower than hand-pollinated fruit set overall, but the highest levels occurred in the middle of the inflorescence. Eumenid wasps and a calliphorid fly were observed to pollinate the flowers, but visits were rare and occurred only during infrequent warm periods.
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    Kengyilia habahenensis (Poaceae: Triticeae) — a new species from the Altai mountains, China (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 103-108 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Triticeae ; Kengyilia habahenensis ; spec. nova ; Taxonomy ; genome analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Kengyilia habahenensis, spec. nova, from the Altai mountains, China, is described morphologically and cytologically. It has 2n = 42 chromosomes, and the genome formula PYS.
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    Phytochemical variation inCondalia microphylla (Rhamnaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 109-114 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rhamnaceae ; Condalia ; Lipid analysis ; seed protein electrophoresis ; chemical variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seed oil composition (sterol esters and sterols) and seed protein profiles ofCondalia microphylla were investigated. The chemical differences observed may be attributed to genotypic changes and could support the existence of infraspecific taxa.
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    Karyological differentiation and speciation in C. MediterraneanAnacamptis (Orchidaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 115-123 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Anacamptis pyramidalis ; A. urvilleana ; Polyploidy ; isolation mechanisms ; speciation ; Flora of the Mediterranean ; Malta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anacamptis pyramidalis is a variable and wide-spread European-Mediterranean taxon. Beside a dominant cytotype with 2n = 36 it includes cytotypes with 2n = 54 and 63 in northern Tuscany (and the Eastern Pyrenees) and one with 2n = 72 on Malta. In contrast,A. urvilleana, formerly often misidentified and included inA. pyramidalis, is a monomorphic and distinct species, endemic to the Maltese Islands. It has 2n = 36, can be clearly separated by morphological and anatomical features and is isolated from partly sympatric populations ofA. pyramidalis with 2n = 72 by differences in chromosome number, flowering time and habitat preference.
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    Chromosomal C-band variation inAllium schœnoprasum (Liliaceae) in eastern North America (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 125-137 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliaceae ; Allium schœnoprasum ; C-banding ; karyotype polymorphism ; geographical variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variation in C-banding was studied in seven populations ofAllium schœnoprasum from eastern N. America, including populations referable to var.sibiricum, var.laurentianum, and ± intermediate. 23 bands were recognized on five pairs of chromosomes, and were treated as 23 loci. No banding site was monomorphic throughout the plants studied. The level of polymorphism per population was 〉60%, and the average heterozygosity values varied from 0.21 to 0.27. The various “banding patterns” of chromosomes were shown to depend on the random combination of individual bands. Nei's genetic distances between populations varied from 0 to 0.070 (mean: 0.033). The matrix of genetic distances was analysed by non-metric multidimensional scaling, and the results showed a significant relationship between longitude and population scores on the ordination. The chromosomal data did not clearly discriminate between the two native varieties ofA. schœnoprasum, but were interpreted as a longitudinal cline. It is suggested that studies of C-banding variation in vascular plants should focus on individual banding sites, rather than on whole chromosome banding patterns.
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    Aestival and autumnal vicariads ofGentianella (Gentianaceae): A myth? (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 139-158 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Gentianaceae ; Gentianella germanica ; Gentianella campestris ; Seasonal dimorphism ; seasonal differentiation ; seasonal ecotypes ; flowering time ; aestival and autumnal vicariads ; grazing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant samples were collected from 13 populations of the two speciesGentianella germanica andG. campestris. In addition, two samples from populations of grazed plants lacking their main stems were collected. A number of relevant morphological characters were measured, the flowering time, and the habitats of each population were studied. Some ecotypes ofG. germanica with clear differences in flowering time were recognized. Differences in flowering time and morphology between populations ofG. campestris seem to be clinal. The generally accepted theory of seasonal dimorphism with the assumption of separate aestival and autumnal vicariads proves to be inadequate. A hypothesis based upon the effect of human influences on the origin of this ecotypes is suggested.
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    An analysis of the B genome speciesArachis batizocoi (Fabaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 159-169 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Fabaceae ; Arachis batizocoi ; A. hypogaea ; Genome analysis ; phylogenetic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Arachis batizocoi Krap. & Greg. is a suggested B genome donor to the cultivated peanut,A. hypogaea L. Until recently, only one accession of this species was available in U.S.A. germplasm collections for analyses and species variability had not been documented. The objective of this study was to determine the intraspecific variability ofA. batizocoi to better understand phylogenetic relationships in sect.Arachis. Five accessions of the species were used for morphological and cytological studies and then F1 intraspecific hybrids analyzed. Some variation was observed among accessions—for example, differences in seed size, plant height and branch length. The somatic chromosomes of accessions 9484, 30079, and 30082 were nearly identical, whereas, the karyotypes of accessions 30081 and 30097 have several distinct differences. For example, 30081 had significantly more asymmetrical chromosomes 2 and 6 and more median chromosomes 7 and 10, and 30097 had significantly more asymmetrical chromosomes 3 and 10 and more median chromosomes 1 and 5 than accessions 9484, 30079, and 30082. All F1 hybrids among accessions were highly fertile. Meiotic observations indicated that hybrids among accessions 9484, 30079, or 30082 had mostly bivalents. However, quadrivalents were observed when either 30081 or 30097 was crossed with the above three accessions and 30081 × 30097 had quadrivalents, hexavalents and octavalents. The presence of translocations is the most likely cause of multivalent formation inA. batizocoi hybrids. Cytological evolution via translocations has apparently been an important mechanism for differentiation in the species.
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    Sex ratio variation and spatial segregation of the sexes in populations ofRumex acetosa andR. acetosella (Polygonaceae) (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 183-195 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Polygonaceae ; Rumex acetosa ; R. acetosella ; Sex ratios ; spatial segregation of the sexes ; environmental correlations ; density effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations ofRumex acetosa andR. acetosella were studied during two growth seasons. The ramet sex ratios ofR. acetosa were always female-biased. InR. acetosella the sex ratios expressed more variation but were mostly female-biased. In both species the sex ratios commonly varied between subpopulations reflecting a partial spatial segregation of the sexes. No marked differences between sexes in vegetative vigour were detected in either species. Interactions between sex ratios, various soil characteristics and population densities were determined. Possible mechanisms for causing biased sex ratios and partial spatial segregation of the sexes are discussed.
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    New taxa ofRubiaceae-Rubieae from Iran (1991)
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    Plant systematics and evolution 174 (1991), S. 197-211 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rubiaceae ; Rubieae ; Asperula sect.Oppositifoliae ; sect. nova ; spec. novae:A. rezaiyensis ; A. rechingeri ; Galium spec. novae:G. anguineum ; G. azerbayjanicum ; G. plurifolium ; G. pseudomegalanthum ; G. kandavanense ; G. wendelboi ; G. sojakii ; G. subvelutinum var.oligotrichum ; var. nova ; G. decumbens ; G. problematicum ; stat. nov ; Flora of Iran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Asperula sect.Oppositifoliae is validated. 2 new species ofAsperula and 7 new species and 1 variety ofGalium from Iran are described, discussed in respect to their affinities and illustrated. 2 subspecies are raised to species rank.
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    Leaf anatomy inTigridieae (Iridaceae) (1991)
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    Plant systematics and evolution 175 (1991), S. 1-10 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Iridaceae ; Tigridieae ; Leaf anatomy ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaf anatomy is described in 32 species of 16 genera of the New World tribeTigridieae (Iridaceae, Iridoideae), including examples from both subtribesCipurinae andTigridiinae. Both plicate (pleated) and foliated (with flanges, or keel extensions) leaf types occur in both subtribes. However, amongTigridiinae, foliated leaves are restricted toTigridia and differ from the foliated leaves ofCipurinae in that they lack subepidermal marginal sclerenchyma, which is present in all the foliated species ofCipurinae. This indicates that the foliated leaf type has evolved at least twice in the tribe, since the plicate leaf, which most closely resembles the equitant leaf typical ofIridaceae, is probably plesiomorphic.
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    An embryological study ofPlatanthera bifolia (Orchidaceae) (1991)
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    Plant systematics and evolution 174 (1991), S. 213-220 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Platanthera bifolia ; Embryology ; embryo sac ; megasporogenesis ; megagametogenesis ; confocal scanning laser microscopy (CSLM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flowers ofPlatanthera bifolia were hand-pollinated and fixed in FPA50 after 2, 5, 7, 14, and 21 days. Ovules, made transparent in Herr's clearing fluid, were investigated using confocal scanning laser microscopy. Pollination initiates the megasporogenesis. Two days after pollination dyads are frequent. Three days later most embryo sacs contain two nuclei. Seven days after pollination the embryo sacs are 4–8-nucleate and some are organized, and a week later all embryo sacs are organized and fertilization takes place. The embryo sac development follows thePolygonum type. Twenty-one days after pollination the egg nuclei have been fertilized and the embryo sacs contain 2- to many-celled embryos. A suspensor is formed during early stages of embryo development but degenerates later. Fertilization of the central nucleus does not lead to endosperm development.
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    Allozyme variation and phylogeny in annual species ofCicer (Leguminosae) (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 11-21 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Cicer ; Allozymes ; isozyme gene duplication ; phylogenetic relations ; polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozymic variation at 30 isozyme loci was examined electrophoretically in nine annual and one perennial species ofCicer. While most of the accessions examined were monomorphic, species can be differentiated on the basis of their enzyme phenotypes. Several groups of species were identified based upon genetic distance values. For example,C. arietinum, C. reticulatum, andC. echinospermum shared the same alleles for most of the loci exmained. PerennialC. anatolicum is also closely related to this group. Similarly,C. judaicum, C. bijugum, andC. pinnatifidum formed another group. Two annual species,C. chorassanicum andC. yamashitae clustered together, whereasC. cuneatum was the most distantly related species. Correlations were found between genetic distances and geographic distribution. Results from enzyme electrophoresis tend to support the previously reported taxonomic treatments based upon crossability and morphological similarity. However,C. yamashitae, which has been classified in the second crossability group, is quite distinct genetically and morphologically from the remaining species of the group. An isozyme gene duplication observed in the genus suggested the monophyletic origin of the species examined in the present study.
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    Restriction data from chloroplast DNA for phylogenetic reconstruction: Is there only one accurate way of scoring? (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 39-54 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rubiaceae ; Chloroplast DNA ; fragment analysis ; restriction analysis ; site analysis ; Wagner parsimony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Information from the same restriction analysis of chloroplast DNA of 33 taxa ofRubiaceae was scored in four different ways, two of which were based on fragments, and two on restriction sites, and they were subsequently analysed with Wagner parsimony. The methods resulted in different phylogenetic trees. The inherent differences between the methods relate to the amount of non-homologous characters and dependent characters, but none of the methods will systematically bias the resulting cladograms. The fragment analyses are much less time-consuming, but probably less accurate, than the site analyses. The choice of method is dependent on a trade-off between accuracy and resources (time). One important recommendation is made: all phylogenetic analyses of chloroplast DNA data should be accompanied by a data matrix and contain information on how the matrix was compiled.
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    Biostatistical studies on western EuropeanDactylorhiza (Orchidaceae)—theD. maculata group (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 55-72 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Dactylorhiza ; D. maculata ; D. fuchsii ; D. saccifera ; D. caramulensis ; Biostatistics ; multivariate analysis ; taxonomy ; morphology ; Flora of Western-Europe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Multivariate analysis tools are exploited on a data set composed of quantitative characteristics collected on 35 populations of plants of theDactylorhiza maculata (L.)Soó group from Western-Europe. These samples lead to four well-defined clusters; this, together with qualitative, cytological and ecological arguments, allows for the recognition of four specific entities:D. maculata s.str.,D. fuchsii (Druce)Soó,D. saccifera (Brongn.)Soó andD. caramulensis (Vermeulen)Tyteca. It is concluded that the floral characters play an essential role in the taxonomical distinction. It also appears that the set of characters measured, as well as the methods exploited, are especially well-suited and valuable tools for the morphological study of the genusDactylorhiza.
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    A biometric study of theOrnithogalum umbellatum (Hyacinthaceae) complex in France (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 73-86 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Hyacinthaceae ; Ornithogalum subg.Heliocharmos ; O. angustifolium ; O. divergens ; O. monticolum ; O. tenuifolium ; O. umbellatum ; Numerical taxonomy ; systematics ; evolution ; Flora of France
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Macromorphological variation within theOrnithogalum umbellatum L. (Hyacinthaceae) complex in France was studied. The resulting data were treated by numerical taxonomy methods. Three morphs can be identified: one corresponding to diploid plants, another made up of triploids and a third which encompasses plants having ploidy level above 3x (4x, 5x, and 6x). A systematic interpretation of the complex is proposed wherein only one species,O. umbellatum, is retained. This species corresponds to a polyploid complex undergoing evolution.
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    Dioecy inMikania (Compositae:Eupatorieae) (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 87-92 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Compositae ; Eupatorieae ; Mikania ; Mikania swartziana complex ; Dioecy ; Flora of the Greater Antilles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For the first time dioecy inMikania and in the tribeEupatorieae is described and discussed. The condition is known only in members of theMikania swartziana Griseb. complex, a group of eight species, all endemic to the Greater Antillean Islands of Cuba, Hispaniola, and Jamaica.
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    A note on the genomic consequences of regular bivalent formation and continued fertility in triploids (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 93-99 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Pennisetum ruppellii ; Pulmonaria longifolia ; Papaver somniferum ; Triploidy ; infragenomic chromosome pairing ; chromosome morphology ; isozyme numbers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genomic evolution of triploid plants with regular bivalent formation is discussed. The conclusion is reached that although all the progeny of an originally triploid individual will be triploid numerically, only part of the progeny will be triploid genomically. The consequences of this for triploid identification by means of chromosome morphology and isozyme numbers is discussed.
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    Archamamelis, hamamelidalean flowers from the Upper Cretaceous of Sweden (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 101-114 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Archamamelis ; Hamamelidaceae ; Hamamelidales ; Hamamelididae ; Cretaceous flowers ; Cretaceous pollen ; Palaeoflora of Sweden
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lignite fossil flowers (including pollen) and isolated stamens of probable hamamelidalean (possible hamamelidaceous) affinities from the upper Cretaceous (Late Santonian or Early Campanian) of Sweden are described. The flowers are 6–7-merous with probably a double perianth, one whorl of stamens and (2-?)3 carpels. The stamens are disporangiate; each theca opens by a valve towards the centre of the flower. Pollen is tricolpate, tectate-columellate and reticulate; the endexine is lamellated in the apertural region. The gynoecium has free styles and a syncarpous ovary. In the one flower that was serially sectioned the ovary is either non-functional or development of the few (2?) ovules is retarded.
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    Gene lineage analysis in populations ofHelianthus niveus andH. petiolaris (Asteraceae) (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 125-138 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Helianthus niveus ; H. petiolaris ; Morphological intergradation ; speciation ; restriction-site variation ; gene lineage analysis ; plant taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Helianthus petiolaris andH. niveus are polytypic species which are morphologically distinct at the periphery of their ranges but intergrade in areas of sympatry.Helianthus niveus includes both annual and perennial members, whereasH. petiolaris is strictly annual. Chloroplast DNA and nuclear ribosomal DNA restriction site data were used to reconstruct the evolutionary history of populations of the two species. Cladistic analyses reveal the following: (1) neither species is monophyletic; (2) the annual habit is derived once in this complex; and (3) the region of morphological intergradation appears to be primary in origin. The significance of interbreeding versus common descent in defining species concepts is discussed in relation to the above cladistic analyses.
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    The tetrapod “DNA fingerprinting” M13 repeat probe reveals genetic diversity and clonal growth in quaking aspen (Populus tremuloides, Salicaceae) (1991)
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    Plant systematics and evolution 175 (1991), S. 115-123 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Salicaceae ; Populus tremuloides ; Alpine community ecology ; clonal organisms ; DNA fingerprinting ; population genetics ; rflp analysis
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    Notes: Abstract A recently developed class of DNA endonuclease fragment probes (variously termed “minisatellite,” “DNA fingerprinting,” or “variable number tandem repeat loci” probes) has detected extensive intraspecific genetic variation in tetrapods. Here we use one probe from this class, the M 13 repeat probe (shown previously to yield ”DNA fingerprints” in humans) to examine genetic diversity in the quaking aspen. Comparisons of endonuclease fragment profiles of individuals separated by at least 6km reveals that diversification of alleles in this species has occurred to such an extent that the likelihood of two randomly chosen individuals having indistinguishableHaeIII fragment profiles is c. 3.17 × 10−4. Based on this finding, members of interdigitating clones can be assigned to one or another clone with high statistical confidence. Interdigitating, morphologically cryptic clones were also identifiable. These results demonstrate that some minisatellite probes can be applied to very distant taxa to obtain useful information about genetic variation.
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    The morphology, taxonomy and evolution ofRhodocoma (Restionaceae) (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 139-160 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Restionaceae ; Rhodocoma ; Speciation ; phylogeny ; culm anatomy ; rhizome anatomy ; morphology ; taxonomy ; Flora of Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vegetative and reproductive morphology, culm and rhizome anatomy and seed surface micromorphology ofRhodocoma are described. It is shown that this variation is best contained by recognizing three new species in the genus. These new taxa are described, and the phylogeny of the genus is investigated by cladistic analysis. The environmental parameters and distributions of the species are related to the cladogram. This suggests that the species are at present ecologically separated, and indicates that the speciation may have been sympatric. This is the first support for the hypothesis that sympatric speciation may have been important in the speciose Cape flora.
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    Glucosinolate spectrum of some AlgerianCruciferae (1991)
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    Plant systematics and evolution 176 (1991), S. 11-20 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Cruciferae ; Glucosinolates ; chemotaxonomy ; GC analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seventeen glucosinolates were identified and quantified by micro-scale GC analysis in Algerian samples fromSisymbrieae, Arabideae, Lepidieae, andBrassiceae tribes of theCruciferae. Major glucosinolates and their amino acid precursors allowed species to fall naturally into tribes as classified byJanchen.
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    The phylogeny and evolution of thePterygodium—Corycium complex (Coryciinae, Orchidaceae) (1991)
    Springer
    Plant systematics and evolution 175 (1991), S. 161-223 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Coryciinae ; Ceratandra ; Evota ; Evotella ; Ommatodium ; Pterygodium ; Anochilus ; Corycium ; Morphology ; phylogeny ; cladistics ; phytogeography ; speciation ; classification ; Flora of southern Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The leaf-anatomy, palynology, seed-morphology, vegetative morphology and especially the highly complicated floral morphology of theCoryciinae s. str. (Diseae: Orchidoideae: Orchidaceae) are described and illustrated in detail. On the basis of these characters the presumed phylogeny, based on a rigorous cladistic analysis, is presented. The cladistic biogeographical analysis of theCoryciinae s. str. shows that it is a member of the Afrotemperate Track, with a pattern of vicariance events typical of the members of this track. An analysis of the patterns of speciation shows that allopatric speciation appears to be rare, and that parapatric speciation across edaphic boundaries may be the most important factor. Proceeding from the information presented, a new classification of the group is proposed in which we recognize the four generaCeratandra, Evotella, Pterygodium andCorycium. The new monotypic genusEvotella comprises a species originally described asPterygodium rubiginosum. The three species of the genusAnochilus are transferred toCorycium andPterygodium. P. magnum, which was originally described asPterygodium but was transferred toCorycium lately, is placed in a monotypic section ofPterygodium.
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    Variation patterns in a leaf beet (Beta vulgaris, Chenopodiaceae) germplasm collection (1991)
    Springer
    Plant systematics and evolution 176 (1991), S. 1-10 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Chenopodiaceae ; Beta bulgaris L ; Germplasm collections ; taxonomy ; single linkage cluster analysis ; principal component analysis ; variation patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to contribute to a better understanding of the variation pattern in leaf beets. 42 biennial samples from a total of 74 entries were described by 17 characters. A group of presumably less selected leaf beets (group A) with narrow petioles was separated from more advanced cultivars by single linkage cluster (SLCA) and principal component analysis (PCA). SLCA sorted the more advanced cultivars into two groups (B and C) based on a simply inherited trait, the leaf colour. These two groups could virtually not be discerned by PCA. Group A contained germplasm similar to provar.vulgaris sensuHelm whereas accessions within group B and C did not easily fit into provar.flavescens. It seems that classical taxonomy does not predict the features of leaf beets precisely enough. It is suggested that this problem can be solved by replacing classical taxonomy in the case of leaf beets by a descriptive database.
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    Chloroplast DNA reassociation and grass phylogeny (1991)
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    Plant systematics and evolution 176 (1991), S. 21-31 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Systematics ; phylogeny ; chloroplast DNA reassociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sequence variation in chloroplast DNA (cpDNA) as measured by DNA reassociation was examined in 12 grass species to address systematic problems in thePoaceae at the subfamilial and tribal levels. Two species,Petunia (Solanaceae) andGlycine (Leguminosae), were included to determine degrees of sequence divergence in cpDNA between monocots and dicots. The data were analyzed phenetically and phylogenetically. Species were segregated into four major groups that corresponded to the subfamiliesPooideae, Oryzoideae, Chloridoideae, andPanicoideae. Representatives of thePooideae andOryzoideae grouped together as did members of theChloridoideae andPanicoideae. ThePooideae split into two major groups corresponding to the recently recognized supertribesTriticanae andPoanae. Internodes between subfamily branches were short which might indicate a burst of divergence in the family early in its evolution. Sequence similarity values between the monocot grass species and the two dicot taxa ranged from 0.15 to 0.27, representing the highly conserved sequences of the chloroplast genome.
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    Effect of the breeding system on the genetic structure in threeCephalanthera spp. (Orchidaceae) (1991)
    Springer
    Plant systematics and evolution 176 (1991), S. 53-61 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; monocotyledons ; Orchidaceae ; Cephalanthera ; Allozymes ; electrophoresis ; genetic variation ; breeding type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic variation of seven enzymes for a total of nine loci was investigated in three species of terrestrial orchids of the genusCephalanthera:C. longifolia, C. rubra, andC. damasonium. These species are characterized by presenting different breeding types: outbreeding , outbreeding with facultative vegetative reproduction, and inbreeding, respectively. Electrophoretic evidence points to a difference in the behaviour of each of the three species which seems strictly related to the breeding type. On the basis of our resultsC. longifolia behaves as a normal outbreeder, whileC. rubra presents the influence of vegetative reproduction in some populations and not in others.C. damasonium shows a total lack of both among and within populations genetic variation, which is most probably due to the autogamic breeding type.
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    Ultrastructure of organelles during microsporogenesis inTillandsia pallidoflavens (Bromeliaceae) (1991)
    Springer
    Plant systematics and evolution 176 (1991), S. 63-74 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Bromeliaceae ; Tillandsia pallidoflavens ; Microsporogenesis ; organelle ultrastructure ; plastids ; periodic acid-thiocarbohydrazine-silver proteinate staining
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract InTillandsia pallidoflavens none of the organelles undergoes fundamental de- and redifferentiation during microsporogenesis. The plastids are amoeboid, exhibit complex internal structures and gradually start accumulating polysaccharides from meiotic prophase I onwards. These observations contradict reports for other taxa. The ultrastructure of mitochondria and dictyosomes, respectively, is more or less orthodox. The extensive ER, which is only poorly stained by standard methods was identified by image intensifiying techniques. The ribosomes are not only associated with the ER or occur as polyribosomes free in the cytoplasm, but can also form more or less dense clusters.
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    Taxonomy and phylogeny of the tribeInuleae (Asteraceae) (1991)
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    Plant systematics and evolution 176 (1991), S. 75-123 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Inuleae s. str. ; Cladistics ; phylogeny ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The interrelationships of the tribeInuleae s. str. have been analysed with a computerized parsimony program (Hennig 86), using theArctotideae as functional outgroup. The results are illustrated with a cladogram and a strict consensus tree. A detailed character discussion is presented. Descriptions of all genera are supplied with brief notes on distribution, references to chemical investigations, and chromosome numbers. Lists of recognized species are also presented in connection to each genus, respectively. 21 new combinations are made, one new genus,Xerolekia A. Anderb., is described,Mollera is reduced to a synonym ofCalostephane, and the genusDuhaldea is resuscitated.Anisopappus was found to be a paraphyletic basal group in the tribe. The paleate generaAsteriscus, Nauplius, Ighermia, Buphthalmum, andXerolekia form one monophyletic group,Inula and other, similar genera were found to constitute the ancestral complex of thePulicaria group.
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    The dimorphic heterostyly inAconogonon campanulatum (Polygonaceae) (1991)
    Springer
    Plant systematics and evolution 176 (1991), S. 125-131 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Polygonaceae Aconogonon campanulatum ; Heterostyly ; floral dimorphism ; pollination ; dioecy ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heterostyly is clearly confirmed inAconogonon campanulatum. This distylous species is dimorphic for tepals, styles, stigma surface, stamens, pollen grain size, and pollen sexine ornamentation. The floral shape is campanulate and thrum flowers are slightly larger than pin flowers. Small solitary bees were observed as flower visitors and probably effected pollination. The possible evolution of dioecy via heterostyly within the genusAconogonon is discussed.
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    Cytological studies inCyclamen subg.Cyclamen (Primulaceae) (1991)
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    Plant systematics and evolution 176 (1991), S. 135-143 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Primulaceae ; Cyclamen hederifolium ; C. africanum ; C. purpurascens ; Chromosome numbers ; karyotypes ; ploidy levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although theCyclamen subg.Cyclamen spp. are morphologically variable, previous studies suggest a superficial cytological uniformity. New chromosome numbers and an indication of karyotypic instability are reported inC. hederifolium andC. africanum that reveal that the cytology of the subgenus is more complicated than previous accounts suggest. The possible significance of these phenomena is discussed. The diploid status ofC. purpurascens has been confirmed and a distinction between the three diploid karyotypes has been described. The cytological variation may help to explain the well documented morphological variation exhibited in these species.
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    Taxonomy and phylogeny of the tribePlucheeae (Asteraceae) (1991)
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    Plant systematics and evolution 176 (1991), S. 145-177 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Plucheeae ; Cladistics ; phylogeny ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The tribePlucheeae (Benth.)A. Anderb., has been analysed cladistically by means of a computerized parsimony program (Hennig 86), using theArctotideae as outgroup. The results of the analysis are presented in a consensus tree and one cladogram. Four major monophyletic subgroups can be recognized: TheColeocoma group (3 genera), thePterocaulon group (3 genera), theLaggera group (6 genera), and thePluchea group (12 genera). All recognized genera are described and most genera are supplied with taxonomical notes including comments on their taxonomic status. Genera such asBlumea, Pluchea, andEpaltes are demonstrated to be unnatural assemblages.Monarrhenus andTessaria are both closely related to thePluchea complex. The old generic nameLitogyne Harv. has been taken up for one species ofEpaltes, the genusRhodogeron is reduced to a synonym ofSachsia, and the following new combinations are made;Litogyne gariepina (DC.)A. Anderb., andSachsia coronopifolia (Griseb.)A. Anderb.
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    Laminar hydathodes inUrticaceae: Survey of tribes and anatomical observations onPilea pumila andUrtica dioica (1991)
    Springer
    Plant systematics and evolution 176 (1991), S. 179-203 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; dicotyledons ; Urticaceae ; Pilea pumila ; Urtica dioica ; Guttation ; hydathodes ; leaf anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laminar hydathodes are known from only three dicot families. InUrticaceae they are associated with minor vein junctions in all five tribes, as surveyed from cleared leaves of 43 species in 30 genera. Only one species lacked hydathodes. Exclusively adaxial hydathodes were found in 28 genera. In tribeElatostemeae, laminar hydathodes inPilea andPellionia species are abaxial, adaxial, or on both surfaces. Guttation was observed in four species.Urtica dioica (adaxial) andPilea pumila (abaxial) were studied anatomically in detail. Hydathodes in the former have normal bundle structure but xylem gaps sometimes occur. In the latter, phloem is displaced in three previously undescribed ways: 1) ends abruptly near hydathode, 2) curves into connecting vein at adjacent junction, or 3) departs xylem, skirts hydathode independently, and rejoins adjacent xylem strand. Laminar hydathodes are a unifying character of theUrticaceae, and they also strengthen its close relationship to theMoraceae.
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    Phenetics andFumaria (1991)
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    Plant systematics and evolution 176 (1991), S. 221-225 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Papaveraceae ; Fumaria ; Phenetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A paper byWilson & al. (1990) on the taxonomy ofFumaria is commented upon. It is concluded that the lack of congruence between the authors' results and evidence from morphology, chemistry, and crossing experiments renders their approach questionable.
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    A new species of the genusSarcocapnos (Fumariaceae) from eastern Andalusia (Spain) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 1-10 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Fumariaceae ; Sarcocapnos ; Systematics ; chorology ; Mediterranean area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A biometric study of theSarcocapnos crassifolia complex from eastern Andalusia (Spain), Algeria, and Morocco was carried out. Twentytwo populations were used in a principal components analysis based on 14 variables. The results support the recognition of two species,S. crassifolia andS. pulcherrima, spec. nova. The taxon described byBoissier asS. speciosa (S. crassifolia subsp.Speciosa) is maintained inS. crassifolia.
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    A new stomatal type inChenopodiaceae (1991)
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    Plant systematics and evolution 177 (1991), S. 11-16 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Chenopodiaceae ; Stomata ; phylogenetic pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new stomatal type—paracytic mesoperigenous—which has not been separated from the paracytic mesogenous type in previous studies of theChenopodiaceae, is described. The frequent occurrence of this previously unknown paracytic mesoperigenous type in this family is demonstrated. As a result a new phylogenetic pathway between anisocytic mesoperigenous and paracytic mesogenous types may be drawn.
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    Glandular trichomes and essential oil constituents ofCalamintha menthifolia (Lamiaceae) (1991)
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    Plant systematics and evolution 177 (1991), S. 17-26 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Lamiaceae ; Satureja group ; Calamintha menthifolia ; Glandular trichome development ; essential oils ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant material ofCalamintha menthifolia was collected from two populations grown in the Vikos-Aoos area (NW. Greece). The structure and ontogeny of the glandular trichomes and the chemical composition of the secreted essential oil were studied. The leaves ofC. menthifolia have numerous glandular trichomes of three morphological distinct types: 1) glandular scales with a unicellular foot and stalk, and a 12-celled head, 2) glandular hairs with a unicellular foot and stalk, and a unicellular pear-shaped head and 3) glandular hairs with a unicellular foot, a bicellular stalk and a unicellular elongated head. Qualitative and quantitative GC-MS analyses of the essential oils revealed piperitone oxide as the main constituent in both populations. In the light of these results the relationships beweenC. menthifolia and other members of theSatureja group as well as its taxonomy are discussed.
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    Structure and function in asclepiad pollination (1991)
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    Plant systematics and evolution 176 (1991), S. 227-253 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asclepiadaceae ; Pollination ultrastructure ; tube germination ; autogamy ; floral biology ; floral structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung An sieben Asclepiadaceen-Arten wird der Zusammenhang von Blütenstrukturen mit dem Bestäubungsprozeß untersucht. Die Analyse erfaßt die Bandbreite von einfacher organisierten (Secamone) bis zu hochdifferenziertenAsclepiadaceae, wobei neben dem offenen Blütentyp auch zwei Formen von geschlossenen Blüten (Sisyranthus, Microloma) untersucht werden. Die Blüten weisen unterschiedlich stark elaborierte Strukturen auf, die als Führungshilfen für den Insektenrüssel dienen. Neben der eigentlichen Leitschiene, die teilweise einen hohen Grad an innerer Differenzierung besitzt, sind vor allem Haare und Coronastrukturen an der primären Führung des Bestäuberrüssels beteiligt. Die interstaminale Lage der Nektarien sowie ihr Hinaufreichen bis zur Leitschiene sichert ebenfalls das Zurückziehen des Rüssels durch die Leitschiene. Die Einführung des Rüssels in den Spalt des Klemmkörpers erfordert einen relativ festen Sitz des Corpusculums, der in den hier untersuchten Arten auf drei verschiedenen Wegen erreicht wird: Anheftung an den Antherenrändern, basales Ankleben am Griffelkopf und Fixierung durch einen distalen Vorsprung des Griffelkopfes. MitTylophora spec. wird ein Fall vorgestellt, bei dem Fremdbestäubung wie auch Auskeimen der Pollenschläuche in situ und damit vermutlich Autogamie zugleich vorkommen. — Die übertragenen Pollinien werden gewöhnlich in die Narbenkammer eingezogen, dort keimen die Pollenschläuche aus und dringen an der Unterseite des Narbenkopfes in diesen ein. BeiSecamone erfolgt der Eintritt der Pollenschläuche an der Flanke des Griffelkopfes, beiMicroloma ist eine exakte Positionierung des Polliniums unnötig, auch vor der Leitschiene abgelegte Pollinien keimen und senden ihre Pollenschläuche durch die innere Leitschiene zum Griffelkopf. BeiSecamone undTylophora ist ein gemeinsamer Anfang der Griffelkanäle (Compitum) im Griffelkopf vorhanden, die Pollenschläuche werden hier auf beide Ovarien verteilt, auch wenn sie nur von einem einzigen eingeführten Pollinium stammen. Bei den übrigen fünf Arten sind beide Griffelkanäle isoliert voneinander, eine direkte Zuweisung der Pollenschläuche eines Polliniums zu nur einem Ovar ist hier die Regel. Damit verfolgen diese höher evolviertenAsclepiadaceae eher die Strategie der resource allocation, indem sie bei der vorherrschenden Belegung mit nur einem Pollinium durch die strukturell gelenkte Zuweisung der Pollenschläuche auch nur ein Fruchtblatt zur Reife bringen müssen.
    Notes: Abstract Aspects of floral biology in relation to floral structures are investigated in seven species ofAsclepiadaceae. Pollinaria removal and insertion by the insect pollinator is aided by various structural devices such as hairs or corona elements guiding the proboscis towards the entrance of the anther slit. The nectary is situated directly below this opening, thus increasing the probability of the proboscis being introduced into the anther slit during retraction. The anther slit itself often displays structural differentiation in adaptation to the guiding of the proboscis and the insertion of a pollinium in cross pollination. These mechanisms are highly elaborated so that they work as well in closed flower types, in which the pollinator does not enter the flower directly, but only introduces its proboscis (Sisyranthus, Microloma). A special feature of pollinaria removal is the variety of ways of fixing the corpusculum against the force of the proboscis when it is drawn into the cleft. — The stigma of all species exceptSecamone is located on the lower surface of the stigma head where it is appressed to the filament tube. In some cases a direct contact of the inserted pollinium with the stigmatic surface does not seem to be necessary for pollen tube germination, probably moistening by nectar suffices in these flowers. WithTylophora spec., a case of in situ pollen tube germination has been studied. — Concerning the path of the pollen tubes, two different strategies are followed.Secamone andTylophora develop a structurally defined compitum, while the other five species have strictly divided stylar canals. In these higher evolved species, the pollen tubes of one inserted pollinium are all directed into one ovary only, thus enabling the plant to allocate its resources to one carpel only in the frequent case of fertilization by one pollinium.
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    A new taxon in the genusMoehringia (Caryophyllaceae) (1991)
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    Plant systematics and evolution 177 (1991), S. 27-38 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Caryophyllaceae ; Moehringia intricata ; Taxonomy ; morphology ; Flora of S. Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The new taxonMoehringia intricata subsp.giennensis, from the calcareous mountains of the south-eastern Iberian Peninsula is described. A comparative morphological study with regard to the most closely related taxa, contributes information of leaf anatomy, seed and pollen morphology, ecology and distribution.
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    Transference of function in the pollination system of theOchnaceae (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 77-80 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Ochnaceae ; Vibrational pollination ; transference of function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Most members of theOchnaceae possess poricidal anthers that are emptied by pollen collecting bees performing vibrational foraging. In several genera, such asTyleria, Adenarake, and various species ofSauvagesia, however, pollen is released by vibration from the anthers through the porus of a novel structure formed by staminodia. These envelop the androecium and gynoecium. Anthers enclosed in this envelope are often longicidal.
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    Phylogenetic and evolutionary implications of nuclear ribosomal DNA variation in dwarf dandelions (Krigia, Lactuceae, Asteraceae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 53-69 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Lactuceae ; Krigia ; Nuclear ribosomal DNA (nrDNA) ; inter-cistronic spacer (ITS) ; intergenic spacer (IGS) ; subrepeating unit ; chloroplast DNA (cpDNA) ; allopolyploid ; restriction site mapping ; methylation ; bootstrap resampling analysis ; sequence divergence value ; cladistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Restriction site and length variations of nrDNA were examined for 51 populations of seven species ofKrigia. The nrDNA repeat ranged in size from 8.7 to 9.6 kilobase (kb). The transcribed region, including the two ITSs, was 5.35 kb long in all examinedKrigia populations. In contrast, the size of the nontranscribed IGS varied from 3.35 to 4.25 kb. Eight different types of length-variations were identified among the 51 populations, including distinct nrDNA lengths in the tetraploid and diploid populations of bothK. biflora andK. virginica. However, a few variations were detected among populations of the same species or within a cytotype. All populations ofKrigia sect.Cymbia share a 600 bp insertion in IGS near the 18 S gene, and this feature suggests monophyly of the section. AllKrigia spp. had a conjugated type of subrepeat composed of approximately 75 basepairs (bp) and 125 bp. Base modifications in the gene coding regions were highly conserved among species. Forty-five restriction sites from 15 enzymes were mapped, 24 of which were variable among populations. Only four of the variable sites occurred in the rRNA coding region while 20 variable sites were detected in the noncoding regions. Collectively, 25 enzymes generated about 66 restriction sites in each nrDNA; this amounts to about 4.3% of the nrDNA repeat. A total of 50 restriction sites was variable, 28 of which were phylogenetically informative. Phylogenetic analyses of site mutations indicated that two sections ofKrigia, sect.Cymbia and sect.Krigia, are monophyletic. In addition, relationships among several species were congruent with other sources of data, such as cpDNA restriction site variation and morphology. Both length and restriction site variation supported an allopolyploid origin of the hexaploidK. montana. The average sequence divergence value inKrigia nrDNA was 40 times greater than that of the chloroplast DNA. The rapid evolution of nrDNA sequences was primarily due to changes of the IGS sequences.
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    Floral scent and intrafloral scent differentiation inMoneses andPyrola (Pyrolaceae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 81-91 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Pyrolaceae ; Pyrola ; Moneses ; Floral scent ; intrafloral scent differentiation ; orientation cues ; poricidal anthers ; pollen flowers ; buzz pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Floral scent was collected by headspace methods from intact flowers, petals, and stamens of four species ofPyrolaceae. The scent samples were analyzed by coupled gas chromatography-mass spectrometry (GC-MS). The floral scent inPyrola spp. is differentiated into a characteristic petal scent—phenyl propanoids and a characteristic stamen scent—methoxy benzenes. InMoneses the scent is characterized by isoprenoids and benzenoids, with a larger proportion of benzenoids in the stamens compared to the petals. Specific anther scents may promote foraging efficiency in buzz-pollinated species and enhance flower fidelity. Variation in floral scent composition is consistent with the taxonomic relationships among the genera and species examined.
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    The karyology of some neotropicalStyracaceae (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 111-115 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Styracaceae ; Styrax ; Pamphilia ; Karyology ; chromosomes ; evolution and systematics in tropical woody plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosome numbers and karyomorphological characters have been investigated inPamphilia andStyrax (Styracaceae). Counted for the first time in the genus, two species ofPamphilia were found to have 2n = 16. The twoStyrax spp. investigated share withPamphilia the same chromosome number, a peculiar condensation behaviour of the chromosomes (Fig. 1a–c) and the same type of semi-reticulate interphase nucleus, results which indicate a close relationship of the two genera. The base number inStyracaceae is probably x = 8 (2n = 2x = 16) with stabilized triploids inHalesia andPterostyrax (2n = 3x = 24). A preliminary comparison withSapotaceae andEbenaceae does not allow a general karyological characterisation of the orderEbenales.
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    Floral anatomy ofHypseocharis (Oxalidaceae) with a discussion on its systematic position (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 161-164 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Oxalidaceae ; Hypseocharis ; Floral anatomy ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The floral anatomy of threeHypseocharis spp. has been studied. The genus resemblesOxalidaceae as well asMonsonia andSarcocaulon of theGeraniaceae. As it is closer toGeraniaceae than toOxalidaceae, it perhaps serves as a connecting link between them.
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    Karyotaxonomical analysis in the genusAngelica (Umbelliferae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 117-138 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Umbelliferae ; Angelica ; Chromosome numbers ; karyotypes ; karyosystematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphometric karyotype characters were studied in 25Angelica spp. (Umbelliferae, Apioideae) and in one species of the related genusTommasinia. For three species the chromosome numbers are new. In our study the majority of the species investigated are diploids with 2n = 22, some are tetraploids with 2n = 44 (for these tetraploids also diploid cytotypes are reported in the literature). Among the diploid species,A. miqueliana has a distinct karyotype consisting of submetacentric and acrocentric chromosomes only, the remaining diploids with 2n = 22 as well as tetraploids with 2n = 44 have rather symmetrical karyotypes, consisting of metacentric and submetacentric chromosomes. The very different chromosome number 2n = 28 has been found inA. gmelinii. Its karyotype includes two distinct groups of chromosomes: 8 pairs of rather large metacentrics and submetacentrics and 6 pairs of very short and asymmetrical chromosomes. Chromosome numbers and structures appear to be useful in the taxonomy of some intrageneric taxa inAngelica.
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    Agmatoploidy inCarex laevigata (Cyperaceae). Fusion and fission of chromosomes as the mechanism of cytogenetic evolution in Iberian populations (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 149-159 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Cyperaceae ; Carex laevigata ; Agmatoploidy ; chromosome fusion ; chromosome fission ; cytogenetic evolution ; Flora of the Iberian Peninsula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper cytogenetic studies on 64 specimens from 20 Iberian populations ofCarex laevigata (Cyperaceae) are presented. Chromosome behaviour in meiosis suggests that the different chromosome numbers obtained (ranging from 2n = 69 to 2n = 80) were distributed according to an increasing geographic gradient of chromosome fission along the North → South direction. Four relatively stable areas were also delimited according to chromosome numbers displayed by this species, i.e. 2n = c. 72, c. 74, c. 76, and 78. The meiotic behaviour ofCarex ×deserta (C. laevigata ×C. binervis) was also studied.
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    Allozymic and morphometric variation inLemna minor (Lemnaceae) (1991)
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    Plant systematics and evolution 177 (1991), S. 139-148 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Lemnaceae ; Lemna minor ; Allozymic variation ; clonal propagation ; morphometry ; cosmopolitan distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozymic and morphometric variation was studied in 28 clones ofLemna minor. This variation was compared with the corresponding variation in four clones ofLemna gibba and four clones ofSpirodela polyrrhiza. A high level of allozymic variation was observed among the clones, despite having been grown under uniform laboratory conditions for several years and despite its quasi-exclusive clonal means of propagation. Based on degree of allozymic similarity,Spirodela polyrrhiza was distinguished from the twoLemna species but the latter species were genetically indistinguishable. Allozymic similarity among clones ofLemna minor was not related to morphometric similarity, nor was it related to the degree of geographic separation or climatic similarity of their sites of origin. The results suggest that allozymic variation among these clones ofLemna minor may be largely neutral and not a consequence of differential selection.
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    rDNA cloning and rapid hybrid identification inPopulus spp. (Salicaceae) (1991)
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    Plant systematics and evolution 177 (1991), S. 165-174 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Salicaceae ; Populus ; Ribosomal RNA genes ; restriction enzyme maps ; rDNA analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribosomal DNA genes fromP. deltoides have been cloned and specific sequences of the 25 S and 18 S rDNA region, labelled by digoxigenin, have been used to determine the rDNA structure ofPopulus tremula, P. fremontii, P. maximowiczii, P. yunnanensis, P. nigra, P. wislizenii, P. alba. The restriction maps of the coding region appeared to be similar among the examined species and with those ofP. deltoides andP. trichocarpa, reported in a previous paper. Inter- and intraspecific variation in rDNA repeat unit length have been revealed after EcoRI digestions. SstI and XbaI restriction sites have been found at different positions in the IGS of some species. The polymorphic fragments generated by SstI digestion allowed the identification of the hybrid origin of some genotypes. The number of rDNA genes in the genome ofP. deltoides has been estimated to be about 2 000 copies. Finally, the usefulness of these studies inPopulus spp. taxonomy and forestry genetics is discussed.
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    Phytoliths as indicators of prehistoric maize (Zea mays subsp.mays, Poaceae) cultivation (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 175-184 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Zea mays subsp.mays ; Opal phytoliths ; paleoenvironments ; cultivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize (Zea mays L. subsp.mays) has been identified in archaeological contexts by a high proportion of large cross-shaped phytoliths. Given the numerous races of maize, this study was undertaken to determine if differences below the species level could be noted. It was also designed to see if phytoliths differed in various plant parts at various stages of growth. Several races were grown under experimental conditions. No significant differences were found. Furthermore, few phytoliths alleged to be diagnostic of maize were discovered. Systemic studies of maize and analyses of prehistoric cultivation by means of phytoliths seem not to be as promising as some researchers have argued.
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    Crossing experiments within theCampanula dichotoma group (Campanulaceae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 185-192 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Campanulaceae ; Campanula dichotoma group ; Hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four supposedly closely related taxa were crossed artificially to test for hybridization barriers. Intra- as well as inter-specific crossings were made. The intra-specific crossings resulted in a high portion of viable hybrids, whereas hybridization barriers were found in all inter-specific combinations except one. The hybrids were non-viable at different levels, viz., (1) no seeds germinated, (2) seeds formed lethal chlorotic seedings, or (3) seeds formed chlorophyllous seedlings which survived the cotyledonary stage, but developed into intermediate forms with low pollen production and/or a strongly reduced pollen viability. Crossings betweenCampanula afra and any of the other three taxa resulted in a non-viable progeny. The crossing capacity amongC. occidentalis, C. kremeri, andC. dichotoma varied. Combinations with large-flowered maternal taxa and small-flowered paternal ones usually failed, whereas a high number of the reciprocal crossings produced hybrids which survived the cotyledonary stage. The hybrid plants varied in pollen viability and pollen production, however. It is concluded that theCampanula dichotoma group should be treated as comprising four distinct species.
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    Karyological investigations inRanunculus subg.Batrachium (Ranunculaceae) on the Aegean islands (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 193-211 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Batrachium ; Ranunculus ; Karyology ; chromosome number ; chromosome morphology ; polyploidy ; Flora of the Aegean islands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper is the first report of an investigation on differentiation and evolutionary pattern inRanunculus subg.Batrachium mainly on the Aegean islands and treats the karyology in the subgenus. The following taxa and chromosome numbers are recorded.R. peltatus subsp.peltatus: 2n = 32, subsp.baudotii: 2n = 32, subsp.saniculifolius: 2n = 16, 32, and 40;R. peltatus s.l.: 2n = 32 and 48;R. penicillatus subsp.pseudofluitans: 2n = 16;R. rionii: 2n = 16;R. sphaerospermus: 2n = 16;R. trichophyllus: 2n = 32, 40, and 48;R. tripartitus: 2n = 48. The karyotypes show certain interspecific differences in chromosome size, in number of chromosome types according to centromere position and in occurrence and position of satellite chromosomes. r-Index and RCL have been calculated.
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    Cytotaxonomic studies of Eastern MediterraneanVicia species (Leguminosae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 221-234 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Papilionoideae ; Vicieae ; Vicia ; Vetch ; chromosome number ; DNA amount ; microdensitometry ; cytotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Collected material of rare and newVicia spp. was investigated from a cytotaxonomic point of view. Nineteen species were examined in total. The study includes 14 novel chromosome counts and measurements of DNA amount, as well as a comparison of chromosome morphology between species. The results of the cytological study support to an extent a recent taxonomical revision of subgenusVicia.
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    Isozyme variation and correspondence with unusual infrared reflectance patterns inPhragmites australis (Poaceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 1-8 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Phragmites australis ; Weeds ; isozyme variation ; infrared reflectance ; polyploidy ; clones ; Mississippi River delta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isozyme variation was investigated in populations ofPhragmites australis (Poaceae) which have recently invaded and taken over marsh habitat of the Mississippi River delta. Infrared aerial photographs in the Garden Island Bay subdelta of the extensiveP. australis populations reveal distinct, clone-like circular patches within a predominant background. Preliminary evidence indicates that the infrared color differences represent distinct morphological types. However, there are no obvious environmental factors that could account for the peculiar patterns.P. australis collections were taken from five separate and distinct “patches” and adjacent “background”. Only two electrophoretic phenotypes were found: one from “patches” and one from the “background”. In comparing the two, 20% of the 40 loci scored are fixed for alternate alleles. These results indicate a clear correspondence of infrared reflectance with electrophoretic phenotype. In addition, the genetic uniformity as evidenced by the discovery of only two electrophoretic phenotypes supports the contention that the recent spread ofP. australis throughout the Mississippi River delta has been primarily, if not exclusively, a result of vegetative propagation.
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    Chloroplast DNA variation among five species ofRanunculaceae: Structure, sequence divergence, and phylogenetic relationships (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 9-25 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Caltha palustris ; Chloroplast DNA ; chloroplast genes ; phylogeny ; restriction site maps ; sequence divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A restriction site map of the chloroplast genome ofCaltha palustris L. (Ranunculaceae) has been constructed for 13 restriction endonucleases using filter hybridization with cloned tobacco chloroplast DNA fragments. A size of 153.8 kb has been estimated for theCaltha chloroplast genome. Forty-six chloroplast genes and four open reading frames have been mapped using small tobacco chloroplast gene probes. Chloroplast DNA sequence divergence has been estimated for all pairs of five species ofRanunculaceae, Caltha palustris, Ranunculus bulbosus, R. fascicularis, R. recurvatus, andTrollius ledebourii, and ranges between 0.2% and 9.6% for the total genome. Divergence values are much higher in the small and large single copy regions than in the inverted repeat. Phylogenetic relationships between the five species have been hypothesized using chloroplast DNA restriction site mapping. One hundred and six informative restriction site mutations have been detected using eleven restriction endonucleases. Cladistic analyses of the restriction site mutations have been performed using Wagner and Dollo parsimony algorithms, and confidence intervals have been calculated for the resulting monophyletic groups using bootstrapping. It is demonstrated that restriction site comparisons are applicable to theRanunculaceae on intergeneric level, with the exception of groups having extensive genomic rearrangements. Moreover, sequence divergence is low enough at the interspecific level to allow phylogenetic analyses within genera such asRanunculus.
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    Lipid content and fatty acid composition in hypogeous organs ofHelleborus species (Ranunculaceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 55-63 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Helleborus viridis ; H. odorus subsp.laxus ; H. niger ; H. foetidus ; Storage lipid ; fatty acid composition ; life form
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Root and rhizome of fourHelleborus species:H. viridis, H. odorus, H. niger, H. foetidus were examined throughout a two-year period in order to determine the variation of lipid content and fatty acid composition during the ontogenetic cycle. In the deciduous geophytesH. viridis andH. odorus subsp.laxus the lipid content reaches its maximum during the quiescent phase, whereas in the evergreen geophyteH. niger the lipid content is highest during the main growth period. In the chamaephyteH. foetidus lipid content is always very low and it does not show variation throughout the year. In all species the fatty acids detected in the neutral fraction are myristic, palmitic, stearic, oleic and linoleic acid. Palmitic and linoleic acid are always present in larger quantities. The pattern of the relative content of saturated/unsaturated fatty acids seems to be linked to the life form of these species.
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    Observations on pollination inSarcostemma (Asclepiadaceae) (1991)
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    Plant systematics and evolution 178 (1991), S. 95-105 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asclepiadaceae ; Asclepiadeae ; Cynanchinae ; Sarcostemma ; Floral anatomy ; floral morphology ; pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field observations on pollination in New World species of the genusSarcostemma R. Br. sensuHolm are reported. Morphological and anatomical comparisons of pollinated flowers ofSarcostemma subg.Ceramanthus Kuntze (New World) andSarcostemma subg.Sarcostemma (Old World) are presented.
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    Circumscription of the tribeCinchoneae (Rubiaceae)—a cladistic approach (1991)
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    Plant systematics and evolution 178 (1991), S. 65-94 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rubiaceae ; Cinchoneae ; Taxonomy ; phylogeny ; cladistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Circumscription of the tribeCinchoneae (Rubiaceae) is reconsidered on the basis of a cladistic analysis of structural data comprising 48 characters (164 states). It is concluded that the tribeCinchoneae, in order to be monophyletic, should be restricted to compriseCapirona, Cephalodendron, Cinchona, Cosmibuena, Dolicholobium, Ferdinandusa, Joosia, Ladenbergia, Macrocnemum, andRemijia. It is also suspected, on insufficient evidence, thatMaguireocharis, Pimentelia, andStilpnophyllum belong here.Alseis, Calycophyllum, Schizocalyx, andWittmackanthus form a monophyletic group possibly related to theCinchoneae. A new tribe,Calycophylleae, is proposed to accommodate them.Hillia, which is possibly the sister group of theCinchoneae, is retained in a separate tribe.Coptosapelta, Corynanthe, Crossopteryx, Hymenodictyon, Luculia, Mitragyna, Mussaendopsis, Paracorynanthe, Pausinystalia, andUncaria are referred to the same tribe, for which the nameCoptosapelteae has to be adopted. Probably alsoGreeniopsis belongs here. The generaCigarilla, Coutarea, andExostema, and possiblySyringantha andWernhamia, seem to be most closely related toPortlandia and should be transferred to the tribeCondamineeae. Bouvardia, Coursiana, Danais, Duidiana, Dunnia, Heterophyllaea, Hindsia, Lecanosperma, Manettia, Merumea, Neohymenopogon, andSchismatoclada should be provisionally transferred to the tribeHedyotideae, which is suspected to be polyphyletic, however. No conclusive results were reached concerning the position ofBalmea, Blepharidium, Emmenopterys, andSuberanthus, the position of them remaining uncertain.
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    Geographical variation and genetic analysis of leaf shape inCrepis tectorum (Asteraceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 247-258 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Crepis tectorum ; Genetic analysis ; geographical variation ; leaf shape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Canonical variate analysis of plants raised in a uniform environment was used to study the pattern of geographical variation in leaf shape ofCrepis tectorum (Asteraceae). The diversity in leaf shape was much greater among populations confined to areas with exposed bedrock in the Baltic region than among weed populations scattered throughout Europe and Canada. A Ward's clustering linked outcrop populations from the archipelago of SW. Finland and the islands of Öland (Sweden) and Saaremaa (Estonia) due to the deeply lobed leaves characterizing these populations, while outcrop populations along the coast of E. Sweden were grouped due to their weakly lobed, narrow and dentate leaves. Most of the weed populations were grouped together but there was no tendency for the variation in this group to be related to habitat or geographical location. A mosaic of variation reflected in sharp (random) differentiation among local populations was superimposed on the large-scale ecogeographical pattern.—Crossing data indicated that most of the variation in degree of leaf dissection is governed by one major gene with deeply lobed leaves dominant over weakly lobed leaves. I suggest that the simple pattern of inheritance may have favoured rapid evolutionary changes in leaf shape, particularly in the Baltic area which emerged relatively late from the sea. Genetic correlations may have constrained the pattern of variation at higher taxonomic levels, since some of the trait associations detected in a segregating F2 generation were also found at the among-population level.
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    Paulownia taiwaniana, a hybrid betweenP. fortunei andP. kawakamii (Scrophulariaceae) (1991)
    Springer
    Plant systematics and evolution 178 (1991), S. 259-269 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Scrophulariaceae ; Paulownia taiwaniana ; P. fortunei ; P. kawakamii ; Isozymes ; morphology ; wood anatomy ; trichomes ; inflorescence grafting ; genetic analyses ; Flora of Taiwan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Paulownia taiwaniana, the widely cultivated, commercially important tree, has been suspected of being of hybrid origin at least since its original publication in 1975. Evidence in support of this thesis, derived from a number of different investigations, is presented in this paper.—Strong evidence comes from a controlled pollination study of the two supposed parental species,P. kawakamii andP. fortunei. F1 seedlings, derived from reciprocal crosses between the suspected parents, exhibited identical banding patterns for a number of enzymes (such as SKDH, GOT, and IDH) withP. taiwaniana, when separated by electrophoresis. Furthermore, comparative morphological studies of trichomes and wood parenchyma patterns between the purported parents andP. taiwaniana reveal that this latter qualitatively exhibits characteristics that combine features of both of the suspected parental types. Biochemically, eight enzyme systems were compared in the three species here under discussion, and, without exception, the electrophoretic banding patterns exhibited byP. taiwaniana represented a combination of the alleles of the other two species. Perhaps the most convincing evidence comes from a genetic analysis of the progeny obtained by selfingP. taiwaniana. Genotypic segregation of the offspring based on a single locus each of SKDH and PGI fit the 1:2:1 hypothesis. Genotypic segregation of the offspring based on two loci each of SP and GOT fit the ratio of 3:6:3:1:2:1. This, taken in conjunction with the other data presented, clearly suggests thatP. taiwaniana is a hybrid involvingP. kawakamii andP. fortunei.
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    URL: http://dx.doi.org/10.1007/BF00937968
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    Studies of Sb and Bi cluster produced by laser desorption (1991)
    Springer
    The European physical journal 19 (1991), S. 203-206 
    Details
    ISSN: 1434-6079
    Keywords: 36.40 ; 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Direct production of cations and anions of metal clusters of Sb and Bi by laser evaporation in a vacuum has been studied. Bulk sample substrates are irradiated by 1064, 532 and 355 nm beams at variable intensity, and the ions produced are accelerated and identified by time-of-flight mass spectrometry. At 1064 nm, the cation distributions show that Sb 3 + and Bi 3 + are the most abundant species, while the monomer and dimer cations are almost non-existent. The anion spectra indicate very low yields of Sb− and Bi− with dominant dimer anion species. These patterns persist with laser power variation within the stable operation domain. With lower incident laser wavelength, the mass distributions are modified, favouring the production of the light cluster ions. In no circumstances were Sb and Bi ions withn〉5 observed. Many of the observed phenomena can be explained if one assumes that for these elements, clusters withn〈6 are formed on the substrate surface. Cluster ions are produced via a prompt desorption process, and are subjected to photon induced reactions due to the same incident laser beam. However, more detailed investigation of the desorption properties will be necessary to confirm such a desorption mechanism.
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    URL: http://dx.doi.org/10.1007/BF01448292
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    STM observation of Au fine-particles on graphite (1991)
    Springer
    The European physical journal 19 (1991), S. 333-335 
    Details
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.16.D ; 82.65.F
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Gold particles deposited on graphite in vacuum have been studied by STM observation in air. Liquid-like coalescence between small gold-particles has been observed near room temperature. Preparation of small particles in vacuum is discussed. Small particles are formed in nucleation process if the degree of coalescence of particles is reduced. Over 400 Au particles of 5 nm in diameters with a narrow size-distribution with FWHM 2 nm and a high density of 3×1012/cm2 is prepared by evaporating gold in a vacuum of about 2×10−5 Torr and at the substrate (HOPG) temperature of 20°C.
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    URL: http://dx.doi.org/10.1007/BF01448323
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    Adsorption — desorption kinetics on epitaxially oriented palladium clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 347-351 
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    ISSN: 1434-6079
    Keywords: 82.65.Jv ; 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Palladium clusters with a low size dispersion and a single crystallographic shape have been obtained by epitaxial growth on (100) MgO. The isothermal adsorption — desorption kinetics of CO is obtained by a molecular beam method allowing the direct determination of the global adsorption probability and of the mean life time of CO molecules on the clusters. Three main results are deduced from these measurements: — an increase of the adsorption rate of CO on the clusters by the capture of CO molecules physisorbed on the substrate, — a faster desorption rate from (100) than from (111) facets at high coverage, — an increase of the adsorption energy for clusters smaller than 3 nm.
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    URL: http://dx.doi.org/10.1007/BF01448326
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    Structural stability and energetics of C, Si, and Ge microclusters: empirical many-body potential energy function calculation (1991)
    Springer
    The European physical journal 19 (1991), S. 423-425 
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    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The structural stability and energetics of carbon, silicon, and germanium microclusters containing 3−7 atoms have been investigated by using a recently developed empirical many-body potential energy function (PEF), which comprises two- and three-body atomic interactions. The PEF satisfies both bulk cohesive energy per atom and bulk stability exactly. It has been found that the most stable C3−4 microclusters are linear withD ∞h symmetry but C5−7 microclusters are planar withD nh symmetry. Silicon and germanium microclusters show similar structural stability. TheX n (X=Si, Ge;n=3−7) microclusters are found to be most stable in the following forms:X 3 is triangular withD 3h symmetry,X 4 is tetragonal withT d symmetry,X 5 is square pyramidal withD 4h symmetry,X 6 is bipyramidal square withO h symmetry, and finallyX 7 is square pyramidal having two atoms underneath withD 2h symmetry.
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    URL: http://dx.doi.org/10.1007/BF01448343
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  • 85
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    C n carbon clusters (n=4−6, 60, 70): interesting cases of computation/observation comparisons (1991)
    Springer
    The European physical journal 19 (1991), S. 431-433 
    Details
    ISSN: 1434-6079
    Keywords: 35.20 ; 36.40 ; 82.30Q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recent theoretical studies proved some of the small carbon clusters C n (n≈1−10) are represented by several isomeric structures. Evaluation of the isomer relative stabilities is necessary for comparison of theoretical data with observation, this being exemplified by the C4 and C6 cases. For the former cluster a new energy estimation has been suggested based on the isomerism reasoning. Relative-stability evaluation for clusters of different dimensions is discussed on the C60/C70 system, pointing out a strong pressure-dependency of the picture. The scheme is matched to the recent observations of Bethune and Meijer.
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    On the shell structure and geometry of monovalent metal clusters (1991)
    Springer
    The European physical journal 21 (1991), S. 271-279 
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    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Hückel model is used to study the electronic structure of monovalent metal clusters. In an fcc cluster the Hückel model gives an estimate to the electronic structure of a free electron cluster. It is shown that the surface faceting of the fcc cluster can destroy the electronic shell structure already when the cluster has about 100 electrons. In the Hückel model the icosahedral structure has smaller total energy than the fcc structures, from which the Wulff construction has the smallest energy already when the cluster has 600 atoms.
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    URL: http://dx.doi.org/10.1007/BF01426385
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    The structure of deposited metal clusters generated by laser evaporation (1991)
    Springer
    The European physical journal 21 (1991), S. 285-288 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 35.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Metal clusters have been produced using a laser evaporation source. A Nd-YAG laser beam focused onto a solid silver rod was used to evaporate the material, which was then cooled to form clusters with the help of a pulsed high pressure He beam. TOF mass spectra of these clusters reveal a strong occurrence of small and medium sized clusters (n〈100). Clusters were also deposited onto grid supported thin layers of carbon-films which were investigated by transmission electron microscopy. Very high resolution pictures of these grids were used to analyze the size distribution and the structure of the deposited clusters. The diffraction pattern caused by crystalline structure of the clusters reveals 3-and 5-fold symmetries as well asfcc bulk structure. This can be explained in terms of icosahedron and cuboctahedron type clusters deposited on the surface of the carbon layer. There is strong evidence that part of these cluster geometries had already been formed before the depostion process. The non-linear dependence of the cluster size and the cluster density on the generating conditions is discussed. Therefore the samples were observed in HREM in the stable DEEKO 100 microscope of the Fritz-Haber-Institut operating at 100 KV with the spherical aberrationc S =0.5 mm. The quality of the pictures was improved by using the conditions of minimum phase contrast hollow cone illumination. This procedure led to a minimum of phase contrast artefacts. Among the well-crystallized particles were a great amount of five- and three-fold symmetries, icosahedra and cuboctahedra respectively. The largest clusters with five- and three-fold symmetries have been found with diameters of 7 nm; the smallest particles displaying the same undistorted symmetries were of about 2 mm. Even smaller ones with strong distortions could be observed although their classification is difficult. The quality of the images was improved by applying Fourier filtering techniques.
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    Neutral mass-selected lead cluster beams (1991)
    Springer
    The European physical journal 19 (1991), S. 199-201 
    Details
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Neutral lead cluster beams with ultra-narrow size distribution were produced by neutralization of mass-selected lead cluster ions, Pb n + withn≤12, in sodium vapor under near-resonant conditions. Absolute charge exchange cross sections were measured as a function of cluster size and are on the order of 40 Å2 forn≥4. Possible fragmentation of the clusters associated with charge transfer was examined by translational spectroscopy. No indication of fragmentation was found.
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    Thermionic emission from giant fullerenes (1991)
    Springer
    The European physical journal 19 (1991), S. 409-412 
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    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Large even-numbered carbon clusters in the size range from 100 to 600 atoms (giant fullerenes) were generated by laser vaporization and directly injected as positive ions via a supersonic beam into the magnetic trap of an ion cyclotron resonance apparatus. Intense laser excitation of the magnetically levitated fullerenes at 4.0 eV was found to result in production of multiply charged fragments in the trap. Details of the time scale and size dependence of this process suggest it is due to thermionic emission from the superheated gas phase clusters.
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    Electronic transitions in C60 and its ions (1991)
    Springer
    The European physical journal 19 (1991), S. 435-438 
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    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electronic spectrum of C60 is calculated using quantum mechanical methods. The first allowed transition in C60 is calculated at an energy of 3.5 eV and with an oscillator strength of 0.09. Several transitions are found at higher energies with comparatively strong oscillator strengths, the strongest one being at 5.78 eV (λ=214 nm). The calculated energy level diagram of C60 is also used to predict wavelengths for transitions in C 60 + and C 60 − . A comparison is made with some recently observed diffuse interstellar bands at 1180 nm and 1320 nm, which have been speculated to originate from C 60 + .
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    Internal excitation effects in the photodissociation of size selected ethylene and methanol dimers (1991)
    Springer
    The European physical journal 18 (1991), S. 181-188 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 82.50.F
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The infrared photodissociation spectra of C2H4 and CH3OH dimers are measured for different internal excitation energies ΔE. The dimers are size-selected in a scattering process with He and the internal energy is varied by using (1) different collision energies, (2) different scattering angles and (3) by measuring the complete energy loss spectra with and without laser radiation by time-of-flight analysis of the scattered clusters. For (CH3OH)2 the width Γ of the spectrum increases strongly with ΔE, while the cross section at the maximum is constant, a normal behaviour for an inhomogeneously broadened system. For (C2H4)2 Γ is nearly constant after a sort of threshold and the cross section increases with increasing ΔE. These results are explained by hot band excitation and the coupling to the darkv 10-mode.
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    Sub-doppler-spectroscopy of Na3 (1991)
    Springer
    The European physical journal 18 (1991), S. 257-265 
    Details
    ISSN: 1434-6079
    Keywords: 33.20 ; 35.20 ; 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Rotationally cold Na3-molecules are formed during the adiabatic expansion of an argon beam, seeded with 5% sodium vapor. With a single mode tunable dyelaser crossing the molecular beam perpendicularly within the ion source of a mass spectrometer the Na3-molecules are excited into levels of the2 A 2-state which are then ionized by acw argon-laser. Rotational lines of the electronic2 A 2 ←X 2 B 2 transition and their hyperfine structure could be resolved using an OODR-technique. A preliminary analysis of the measured spectra is discussed and a comparison of the experimental results with ab initio calculations is presented.
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    Calculation of photoionization cross sections of Na2–8 and K2–8 clusters (1991)
    Springer
    The European physical journal 18 (1991), S. 267-280 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 33.80E
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Analysis of free metal clusters studied with photoionization mass spectrometry or photoelectron spectroscopy requires theoretical predictions of the photoionization cross sections to gain a deeper physical understanding. Calculated energy-dependent photoionization cross sections of Na2–8 and K2–8 clusters are presented in this study. The ground state electronic structure of the clusters are calculated using the Local Spin Density method (LSD) which is also the starting point for the cross section calculation with the continuum multiple scattering method. A basic analysis of the photoionization process is given within the independent electron picture. Strong resonances are predicted in the UV cross sections (5–10 eV) of K3–8 but not for Na3–8, interpreted as shape resonances, i.e. quasibound states in which electrons are trapped by a potential barrier. Unfortunately experimental data are only known close to the ionization threshold and a comparison between our values and experimental data in a broad energy range is not possible.
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    Computer simulations of small semiconductor and metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 31-36 
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    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A brief survey is presented of recent simulations of small clusters, made with both ab-initio and classical approaches, with particular emphasis on the application of the Car-Parrinello method. The discussion mainly focusses on the structural properties of a variety of materials and on the effects of temperature.
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    The influence of shells, electron thermodynamics, and evaporation on the abundance spectra of large sodium metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 47-50 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 35.20.Wg ; 03.65.-w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the mass abundance spectra of sodium clusters containing up to 600 atoms are presented. The clusters are produced in a seeded supersonic expansion of Ar or Kr gas, and the spectra are obtained by a time-of-flight technique. The sawtooth features in the spectra are interpreted as evidence of a regular spherical shell structure with magic numbers,N 0, scaling approximately with the cube root of the number of sodium atoms. Altogether twelve shell closings are observed,N 0=2, 8, 20, 40, 58, 92, 138, 196, 260, 344, 440 and 558. There is also a pronounced odd-even staggering all the way up toN=70. The experimentally observed intensity changes for the clusters around the magic numbers are discussed in terms of the electronic free energy,F(N), calculated at finite temperature, and the second differences of the free energy Δ2 F(N)=F(N−1)−2F(N)+F(N+1). The processes behind the non-uniform abundance distributions, and the thermodynamics of finite electron systems with non-uniform level spacings are discussed on this basis.
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    Semiclassical variational study of size effects in neutral and charged jellium droplets (1991)
    Springer
    The European physical journal 19 (1991), S. 55-58 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 31.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r s Z 1/3, withZ=vN andr s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr s . Terms of volume (R 3), surface (R 2), curvature (R), constant (R 0), (1/R) and (1/R 2) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r s ), and surface energies σ(r s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP≃W+β/R andAF≃W+δ/R.
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    Absolute cross sections for electron impact ionization of Ag2 (1991)
    Springer
    The European physical journal 19 (1991), S. 77-79 
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    ISSN: 1434-6079
    Keywords: 34.80G ; 36.40 ; 35.20V
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The previously measured relative cross section function for electron impact ionization (EII) of neutral Ag2 has now been calibrated quantitatively by combining the electron impact ionization with in situ non resonant two photon ionization (NR2PI). By comparing the NR2PI saturation intensities measured for Ag 2 + and Ag+ with the corresponding EII intensities, the ratio between the electron impact ionization cross sections (EIICS) of neutral Ag2 and Ag was determined to be σAg2/σAg=1.53 for an electron energy of 46 eV. This result agrees well with the geometricn 2/3-rule $$(\sigma X_n \sim n^{2/3} )$$ commonly proposed for the dependence of the EIICS of clustersX n on the cluster sizen.
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    Thermal broadening of plasmon absorption in potassium cluster ions (1991)
    Springer
    The European physical journal 19 (1991), S. 85-87 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 78.40-q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The optical absorption spectrum around the surface plasmon peak is presented for K 21 + . Hot, charged potassium clusters are produced by an adapted liquid metal ion source. The plasmon is found to be slightly red shifted from and distinctly broader than the one reported in an experiment on colder clusters by Bréchignac et al. [3]. Mechanisms responsible for the temperature dependence of the width and position of the surface plasmon in small metal clusters are discussed.
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    Response properties of sodium clusters within a jellium-like model with finite surface thickness (1991)
    Springer
    The European physical journal 19 (1991), S. 93-96 
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    ISSN: 1434-6079
    Keywords: 36.40 ; 71.45.G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The usual spherical jellium model of alkaline clusters is generalized to allow for a finite surface thickness in the positive background distribution. Static (relative stability, ionization potentials) and response properties have been calculated and the results show a better agreement with experiments.
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    URL: http://dx.doi.org/10.1007/BF01448263
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    The elastic scattering on jellium clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 97-99 
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    ISSN: 1434-6079
    Keywords: 34.80.B ; 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The following calculations are based on the local density approximation potential (LDA) of W. Ekardt for the spherical jellium-background model (SJBM). Taking into account the smooth shape of the potential, the WKB approximation was used to calculate the energy and angular dependence of the electron scattering cross-sections fo rsmall Na clusters. The number of phase shifts needed to describe the scattering in the range of energies 〈4.5 eV increases with the size of cluster. The calculated elastic electron scattering cross-sections for the Na clusters, corresponding to the shell closings (8, 20, 40), are exhibiting a pronounced peak structure, correlated with resonance states. The computed peaks of the angular dependences of the cross-sections on energy are shifted to small angles with increasing the cluster size. The absence of fragmentation at these small electron energies presents a challenge for the experimentalists.
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    URL: http://dx.doi.org/10.1007/BF01448264
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