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  • Angiosperms
  • Springer  (7)
  • 1995-1999
  • 1990-1994  (7)
  • 1994  (7)
Collection
Keywords
Publisher
  • Springer  (7)
Years
  • 1995-1999
  • 1990-1994  (7)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Nucleotide distribution in gymnosperm nuclear sequences suggests a model for GC-content change in land-plant nuclear genomes (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 34-46 
    Details
    ISSN: 1432-1432
    Keywords: CpG suppression ; GC content ; Angiosperms ; Isochores ; GC bias ; Mutational pressure ; Error-prone repair ; Transcriptionally coupled repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nuclear protein coding sequences from gymnosperms are currently scarce. We have determined 4 kb of nuclear protein coding sequences from gymnosperms and have collected and analyzed 〉60 kb of nuclear sequences from gymnosperms and nonspermatophytes in order to better understand processes influencing genome evolution in plants. We show that conifers possess both biased and nonbiased genes with respect to GC content, as found in monocots, suggesting that the common ancestor of conifers and monocots may have possessed both biased and nonbiased genes. The lack of biased genes in dicots is suggested to be a derived character for this lineage. We present a simple but speculative model of land-plant genome evolution which considers changes in GC bias and CpG frequency, respectively, as independent processes and which can account for several puzzling aspects of observed nucleotide frequencies in plant genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178247
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  • 2
    Electronic Resource
    Electronic Resource
    The characterisation and identification of a naturally occurring hybrid in the genusLeucaena (Leguminosae: Mimosoideae) (1994)
    Springer
    Plant systematics and evolution 192 (1994), S. 177-197 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Leucaena esculenta ; L. leucocephala ; Hybridization ; sterile triploid ; morphometric analysis ; DNA characters ; restriction site analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytogeographical, morphological, and molecular evidence for the widespread but sporadic occurrence of sterile hybrids betweenLeucaena leucocephala subsp.glabrata andL. esculenta subsp.esculenta in South-Central Mexico is presented. Most morphological and DNA characters studied in the putative hybrids showed states intermediate between the proposed parental taxa. The occurrence of non-additive nuclear ribosomal DNA phenotypes is discussed and the need to use a suite of nuclear taxon-specific markers to determine hybridity is emphasized. The origin of the hybrid is discussed in relation to the disruption of the distributions of both parental taxa through use by man as minor food plants, providing another example of the important influence of human interference on the evolution ofLeucaena. The successful use of dried leaf material as a source of DNA is highlighted as an efficient way to identify sterile hybrids at the molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00986251
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  • 3
    Electronic Resource
    Electronic Resource
    Chemistry and micromorphology of compound epicuticular wax crystalloids (Strelitzia type) (1994)
    Springer
    Plant systematics and evolution 193 (1994), S. 115-123 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Strelitzia ; Heliconia ; Typha ; Benincasa ; Epicuticular wax ; wax ultrastructure ; wax chemistry ; systematics ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Certain non-liliiflorous taxa within the monocotyledons (e.g.,Strelitzia, Heliconia, Typha) are characterized by compound epicuticular wax rodlets (Strelitzia type). Similar rodlets are also encountered on the surface of the dicotyledonous plantBenincasa hispida (Thunb.)Cogn. Chemical analysis of the surface wax from both sources showed that the rodlets are chemically distinct. The rodlets of the monocotyledons consist exclusively of aliphatic wax lipids, mainly wax esters. In contrast, the rodlets ofBenincasa are cheifly composed of triterpenol acetates and triterpenols. Formation of rodlets is therefore interpreted as ultrastructural convergency. It is concluded that taxonomical studies on wax crystalloids can be misleading when interpreted in terms of micromorphology of crystalloids only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00983545
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  • 4
    Electronic Resource
    Electronic Resource
    Gynoecium and perianth inZanthoxylum s.l. (Rutaceae) (1994)
    Springer
    Plant systematics and evolution 189 (1994), S. 165-191 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Rutaceae ; Zanthoxylum ; Fagara ; Flower morphology ; perianth ; gynoecium ; acrostylous and anacrostylous-basistylous carpels ; compitum ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The question whether the uniseriate perianth ofZanthoxylum L. s. str. is homologous with the calyx or the corolla of taxa included inFagara, or of an independent origin, has been controversial for a long time, but the arguments mostly have remained theoretical. The present investigation of floral structures indicates that there are two different types of uniseriate perianth inZanthoxylum s. str. Therefore, this taxon does not represent a natural group and should be united withFagara asZanthoxylum s.l. The infrageneric taxonomy of this genus is still very ambiguous. It is shown that differences in indumentum, number of sepals and petals (5-4-3) resp. perianth segments (4–9), stamens (3–6), and free carpels (1–5) are of systematic relevance. Particularly important but so far neglected is carpel shape, where an acrostylous and an anacrostylous-basistylous type can be recognized. Stigmata of 2 or more carpels mostly fuse to form a compitum. 4–5-merous flowers with calyx and corolla, and acrostylous carpels are considered as plesiomorphic character states in the genus. On the basis of ± corresponding morphological and phytochemical progressions a working hypothesis about the relationships withinZanthoxylum s.l. is presented in graphical form (Fig. 9).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00939724
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  • 5
    Electronic Resource
    Electronic Resource
    Merosity in flowers: Definition, origin, and taxonomic significance (1994)
    Springer
    Plant systematics and evolution 191 (1994), S. 83-104 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; androecium ; Merosity ; phyllotaxis ; pseudowhorl ; zygomorphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The term merosity stands for the number of parts within whorls of floral organs, leaves, or stems. Trimery is considered to be a basic condition that arose through the cyclisation of a spiral flower. Pentamery is mostly derived from trimery by the repetitive fusion of two different whorls. Dimery is either directly derived from trimery, or through pentamery as an intermediate stage. Tetramery is linked with pentamery and should not be confused with dimery. Possible causes for a change in merosity are the reduction of the number of carpels and zygomorphy in flowers. Derivations of different merosities have important consequences for the arrangement of the androecium (the insertion of stamen whorls, their identifications, and their number). It is concluded that two main groups can be identified within the angiosperms: magnolialean and monocotyledonean taxa are mostly trimerous or dimerous; non-magnolialean dicots are mostly pentamerous or tetramerous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985344
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  • 6
    Electronic Resource
    Electronic Resource
    cpDNA intergene sequences corroborate restriction site data for reconstructingRubiaceae phylogeny (1994)
    Springer
    Plant systematics and evolution 190 (1994), S. 245-248 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Rubiaceae ; Chloroplast DNA ; atpB-rbcL intergene region ; phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Representatives of seven genera from five tribes ofRubiaceae have been compared in respect to a non-coding intergene cpDNA region of about 1000 bp, situated between the atpB and the rbcL genes. The resulting most parsimonious PAUP cladogram corresponds very well with one based on total cpDNA restriction site data obtained byBremer & Jansen (1991). The two different molecular analyses thus corroborate each other and contribute to an improved systematic arrangement of the large family, e.g., in respect to placing the tribeHedyotideae clearly into the subfamilyRubioideae, closer toRubieae than toPsychotrieae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00986196
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  • 7
    Electronic Resource
    Electronic Resource
    Floral structure and evolution of primitive angiosperms: Recent advances (1994)
    Springer
    Plant systematics and evolution 192 (1994), S. 79-97 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; paleoherbs ; Magnoliidae ; Gnetales ; Floral evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concepts of primitive angiosperm flowers have changed in recent years due to new studies on relic archaic groups, new paleobotanical finds and the addition of molecular biological techniques to the study of angiosperm systematics and evolution.Magnoliidae are still the hot group, but emphasis is now on small primitive flowers with few organs and also on the great lability of organ number. Of the extant groups, a potential basal position of the paleoherbs has been discussed by some authors. Although some paleoherbs have a simple gynoecium with a single orthotropous ovule, anatropous ovules may still be seen as plesiomorphic in angiosperms. Anatropy is not necessarily a consequence of the advent of closed carpels. It may also exhibit biological advantages under other circumstances as is the case in podocarps among gymnosperms. Valvate anthers have now been found in most larger subgroups of theMagnoliidae (recently also in paleoherbs) and in some Cretaceous fossils. Nevertheless, as seen from its systematic distribution, valvate dehiscence is not necessarily plesiomorphic for the angiosperms, but may be a facultative by-product of the thick connectives and comparatively undifferentiated anther shape inMagnoliidae and lowerHamamelididae. A perianth is relatively simple in extantMagnoliidae or even wanting in some families. In groups with naked flowers the perianth may have been easily lost because integration in the floral architecture was less pronounced than in more advanced angiosperm groups. Problems with the comparison of paleoherb flowers with those ofGnetales are discussed. The rapid growth of information from paleobotany and molecular systematics requires an especially open attitude towards the evaluation of various hypotheses on early flower evolution in the coming years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985910
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