ALBERT

Description: A summary will be given at the end of part 2 of this paper.

Description: The Zuideindigerwiede is a lake in the north-western part of the province of Overijssel (The Netherlands). The eastern part shows a succession of nymphaeids and helophytes. This series is exposed to the prevailing winds. The western part shows a succession of stratiotids, hydrocharids and pleustophytes and of \xe2\x80\x98sapropelophytes\xe2\x80\x99. In both cases there is an increase in vegetational structure, especially in the number of growth forms. Secundarily, a zonation of Ceratophyllum demersum may establish itself before the Stratiotes-zonation and a zonation of Calla palustris develops as a fringe around the floating islands. When \xe2\x80\x98isolation\xe2\x80\x99 of small masses of water occurs, a vegetation rich in Utricularia vulgaris may develop in places where the water is shallow and Stratiotes has died off. The second series proceeds more rapidly than the first, the sapropelium being deposited along the western shoreline by an undercurrent, caused by the dash of waves against the opposite bank. Special attention is focussed on several interesting species, such as Azolla caroliniana and Calla palustris. Generally the succession series exhibits the same trends in other lakes in the Netherlands. In more extreme situations only a part of the series is developed, and in the most extreme case only the elode\xc3\xafd-phases occur. The submerged stages of nymphaeids, helophytes and stratiotids show \xe2\x80\x99transitions\xe2\x80\x99 to elodeids in an ecological sense.

Description: Cardamine pratensis L. in the Netherlands 242 specimens of the Cardamine pratensis aggregate from 58 Dutch localities were morphologically and cytologically studied. Two forms could be distinguished, viz. a form with usually lower chromosome numbers (2n = 28\xe2\x80\x9432, rarely up to 52), and another with higher chromosome numbers (2n = 56\xe2\x80\x9484), which, judging by the criteria applied by L\xc3\x96VKVIST (12), correspond with C. pratensis sensu stricto and C. palustris (Wimm. & Grab.) Peterm. respectively. The frequent occurrence of \xe2\x80\x98transitional\xe2\x80\x99 forms and of specimens which are difficult to place, in conjunction with a number of cytological, genetical, and geographical arguments, make the present authors feel that, chiefly for practical reasons, it is preferable to treat the two forms as subspecies. The two taxa can be clearly distinguished in many, though not in all, instances. The following differential characters are considered to be of diagnostic value: C. pratensis L. subsp. pratensis (fig. 1, a and 2, a\xe2\x80\x94e): rosette leaves smaller with a mean number of pinnae of 4.1; segments of cauline leaves in most cases sessile and smaller; stem usually straight and erect, but rarely over 30 cm tall; mean number of flowering lateral shoots 3; mean value of length of sepals 3.6 mm, of width 2.0 mm; mean length of petals 10.3 mm and mean width 5.5 mm; mean length of filaments 3.4 and 5.2 mm and of anthers 1.7; mean length of siliqua 27 mm; chromosome number usually varying between 28 and 32; flowering season starting relatively early; a nocturnal nastic change of position (\xe2\x80\x98sleeping\xe2\x80\x99) of the flower; vegetative propagation organs rarely developed; prefers a relatively drier habitat, mainly in grasslands and in forests on basic soils. C. pratensis L. subsp. palustris (Wimm. & Grab.) Janchen (fig. 1, b\xe2\x80\x94d and 2, f\xe2\x80\x94j): rosette leaves larger with a mean number of pinnae of 5.5, segments of cauline leaves usually petiolulate and broader, to broadly elliptic in outline; stem thicker, stouter and more fleshy and frequently showing a torsion about the longitudinal axis; number of flowering lateral shoots upon the average 1, in addition vegetative side shoots often present; mean length of sepals 4.7 mm, mean width 2.5 mm; mean length of petals 12.7 mm, their mean width 7.6 mm; colour of corolla often lighter (to almost completely white); mean length of filaments 4.5 and 6.6 mm and of anthers 2.3 mm; mean length of siliqua 38 mm; chromosome number 56\xe2\x80\x9484; flowering season starting one to two weeks later; no nastic changes in position (\xe2\x80\x98sleeping\xe2\x80\x99) of flower; adventitious shoots common on rosette leaves, sometimes (also) on stem leaves; prefers wetter habitats, especially in riparian and \xe2\x80\x98floating island\xe2\x80\x99 vegetation and in elder carr. The nature of these differences is characteristic of many similar cases of polyploidy (disploidy) and has no specific qualitative indication value. It is feasible that after a more detailed analysis \xe2\x80\x98cytoclines\xe2\x80\x99 can be recognized. There is some evidence for the view that the cytological and morphological range in variation is relatively large in habitats which are instable in an ecological sense and relatively small in stable habitats.

Description: The genus Parietaria L. in the Netherlands, 1 & 2.\nA study of herbarium specimens and of living plants of both species of Parietaria occurring in the Netherlands permits the following conclusions: 1. Both species can not possibly be conspecific on account of the constant differences in the morphology of the inflorescence, in the chromosome number, and in their periodicity, ecology and distributional areas. 2. The binomial Parietaria judaica L. 1756 has priority over the name P. diffusa proposed by Mertens & Koch in 1823, and the illegitimate name P. ramiflora Moench 1794. 3. The two species can be distinguished as follows: P. officinalis L., Sp. Pl., 1753, p. 1052. Syn.: P. erecta Mert. & Koch 1823; P. officinalis L. var. erecta (Mert. & Koch) Weddell 1857; P. officinalis L. subsp. erecta (Mert. & Koch) B\xc3\xa9guinot 1908. Stem usually erect, branched or unbranched, (20\xe2\x80\x94) 50\xe2\x80\x9470 (\xe2\x80\x94160) cm tall, 3\xe2\x80\x946 mm in diam., as a rule scantily pubescent, green or faintly erubescent, hollow; in the autumn with red hibernation buds. Leaves comparatively large, (5\xe2\x80\x94) 8\xe2\x80\x9412 (\xe2\x80\x9420) cm long, ovate-oblong, often long-acuminate; the blades from about 3 to about 5 times as long as the petiole. Inflorescences almost invariably multiflorous, forming dense clusters of flowers. Bracts of the flowers of the cincinnate portions of the cymes free at the base. Perigone after anthesis not or hardly accrescent, 2 mm long, closed around the 1,5 mm long nutlet. Haploid chromosome number: n = 7. P. judaica L., Fl. Palaest., 1756, p. 466. Syn.: P. ramiflora Moench 1794, nom. illeg.; P. diffusa Mert. & Koch 1823; P. officinalis L. var. diffusa (Mert. & Koch) Weddell 1857: P. officinalis L. var. ramiflora (Moench) Aschers. & Graebn. 1911; P. officinalis sensu Jarmolenko 1941, non L. Stem usually ascending or prostrate, frequently ramified, (3\xe2\x80\x94) 20\xe2\x80\x9440 (\xe2\x80\x94110) cm long, 2\xe2\x80\x943 mm in diam., usually densely pubescent, darkred, pithy; not forming hibernation buds (in springtime new shoots are produced from the rhizome). Leaves comparatively small, (1\xe2\x80\x94) 4 (\xe2\x80\x946) cm long, ovate, often shortly acuminate; the blades from about 2 to about 3 times as long as the petiole. Inflorescences usually pauciflorous, forming small lax clusters. Bracts of the flowers of the cincinnate portions of the cymes connate at the base. Perigone manifestly accrescent after anthesis, 3 mm long, slit open; nutlet 1 mm long. Haploid chromosome number; n = 13. 4. It seems highly probable that a tetraploid form of P. officinalis or a closely allied taxon must have been one of the parent forms when the taxon P. judaica originated. 5. P. judaica exhibits a marked preference to walls as a habitat, whereas P. officinalis prefers growing under shrubs or in other sheltered (and often ruderal) sites. 6. Of the two, only P. judaica is a species of mediterranean-atlantic distribution; the principal area of distribution of P. officinalis lies presumably in the Danube countries of central Europe and in the Balkans. 7. P. judaica may be considered to be truly native in this country in the so-called Fluviatile District, but P. officinalis is probably an escape from cultivation.

Description: The sterile hybrid of Carex diandra Schrank and C. paniculata L. was found in two localities in the north-western part of the province of Overijssel in disturbed peat bog vegetations. The literature referring to this hybrid is reviewed. The name Carex X beckmannii F. W. Schultz was published in 1887, and, if published with a description, has priority over the name C. X germanica Richter ex Aschrs. & Graebn., 1902.\nThe habitats of the hybrid are compared with those of the typical forms of the parents, and of a densely tufted form of Carex diandra which is rather common in the above-mentioned region.

Description: Pteridological Notes, 3 The genus Polypodium in the Netherlands Both Polypodium vulgare L. (sensu stricto) and P. interjectum Shivas occur in the Netherlands. Most of the differential characters reported in the literature overlap one another rather broadly, so that it is often necessary to use a \xe2\x80\x99syndrome\xe2\x80\x99 of characters for the naming of individual specimens. The results obtained by the present authors do not correspond with those of SHIVAS (22), ROTHMALER & SCHNEIDER (18), or LENSKI (11) in every respect. The two forms appear to differ in the following features: P. vulgare: Frond lanceolate in outline with the lower pairs of pinnae approximately of equal length along a considerable portion of the frond blade, and the apical part often gradually attenuate. Pinnae with a rounded, obtuse or occasionally acute apex and hardly incised to dentate or serrate margins. Colour of foliage bright or dark green, rarely greyish-green. Sori usually situated closer to the midrib than to the margin or approximately half-way between them. Immature sori orbicular, rarely broadly elliptic, frequently reddish brown. Number of indurated annulus cells 10\xe2\x80\x9415 (\xe2\x80\x9423), mean number 12 per sporangium, about 70 \xc2\xb5 broad; number of basal cells 1 (sometimes 2); these cells relatively small. Paraphyses absent. Spores (45\xe2\x80\x94) 55\xe2\x80\x9475(\xe2\x80\x9488) \xc2\xb5 long and 27\xe2\x80\x9460 \xc2\xb5 broad, upon the average 62 by 40 \xc2\xb5. Scales of the ramentum of the rhizome usually somewhat smaller than those of P. interjectum (but fragile in both species and hence in herbarium specimens not so completely preserved as to provide a reliable diagnostic character). As a rule spores maturing earlier than those of P. interjectum. Chromosome number: n=74 or 2n=148. P. interjectum: Frond narrowly ovate to triangular-ovate in outline, with some of the lower pairs of pinnae distinctly longer than the more distal ones, and frequently rather abruptly narrowed into a long-attenuate apex. Pinnae with acuminate apex and usually serrate margins. Colour of foliage nearly always greyishgreen. Sori usually closer to the margin than to the midrib, occasionally half-way between them, frequently somewhat smaller than those of P. vulgare. Immature sori elliptic, usually ochreous, more or less suffused with orange, in colour. Number of indurated annulus cells 6\xe2\x80\x9411 (mean number 9), about 80 \xc2\xb5 broad, number of basal cells 2\xe2\x80\x944; these cells relatively large. Paraphyses absent or sometimes small, unbranched or only somewhat branched paraphyses present. Spores (60\xe2\x80\x94)65\xe2\x80\x9488(\xe2\x80\x94100) \xc2\xb5 long and 35\xe2\x80\x9470 \xc2\xb5 broad, upon the average 75 by 50 \xc2\xb5. Scales of ramentum of rhizome upon the whole somewhat longer and broader than those of P. vulgare. Spores usually maturing 2 to 4 weeks later than those of P. vulgare. Chromosome number: n=111 or 2n=222. Supposed differences in the ratio between the lengths of the frond petiole and the frond blade, in the degree of branching of the leaf veins, and in the position of the lowermost pinnae in respect of the plane of the frond blade, do not hold. The sterile hybrid, P. X mantoniae Rothm., was recorded in several localities. In a few cases it was found growing among the parent species in habitats disturbed by human activities. Such habitats seem to be particularly suitable for the settlement of hybrid specimens and thus provide a site for possible introgression. In some instances heterosis was manifest and monstruosities were also encountered. In our opinion morphological malformations are of a relatively more frequent occurrence among hybrids or among forms with reduced fertility due to introgression. P. vulgare is often found in more acid environments but is not calcifugous. It also occurs on calcareous rocks and limestone walls (or walls built with lime mortar). P. interjectum presumably has somewhat higher requirements as far as the degree of trophism is concerned. In the Netherlands it occasionally grows on pollard willows (Salix alba), in a characteristic combination of species including, e.g. Solanum dulcamara, Galeopsis tetrahit, and Poa trivialis, and with a strikingly high proportion of berry-producing shrubs, birds being most probably responsible for the high nitrogen content of this particular habitat which can be deduced from the presence of a considerable number of nitrophilous species. P. vulgare is common throughout a large part of the Netherlands, whereas P. interjectum is chiefly found in the calcareous dunes and in the fluviatile district of the lower regions of the rivers Rhine and Meuse.

Description: The lichen Ramalina intermedia Del. apud Lamy was found near Apeldoorn on a decayed wall of an old castle in the possession of the Royal family. The wall, rising up from the castle moat, dates from the 16th century, but remained covered with soil for several centuries after the moat had been filled up with earth, only to be dug out again during restoration work in 1904. R. intermedia has not been previously recorded from the Netherlands. At the Apeldoorn site it occurs together with Gyroweisia tenuis, a moss of rare occurrence in this country.

Description: Flat forms of Lemna gibba (fig. 1, a\xe2\x80\x94c) occur rather commonly and differ in several characters from L. minor (fig. 1, d\xe2\x80\x94e), e.g.: The largest diameter of the air cavities below the lower surface of the discs averages 0,19 mm in L. minor, 0,36 mm in flat growth forms of L. gibba and 0,47 mm in swollen growth forms of the latter. In L. gibba the walls of the cavities are thicker than in L. minor. L. minor is usually more convex above and the shape of the discs is more elongate than in L. gibba. L. minor is bright green, L. gibba more greyish green suffused with reddish purple. Pigmentation, if present, starts at the edges of the discs in L. minor and in the centre of the upperside in L. gibba. Discs of L. minor are often found in groups of 5 or more (up to 32), in flat L. gibba this forming of groups of young discs is less distinct, though not rare (up to 8). L. minor occurs in relatively poor waters, especially after pollution with substances of an organic nature (such as drain water and manure). This species appears to be faithful to the Lemno-Spirodeletum. It also occurs in the Ricciocarpo-Lemnetum. L. gibba prefers more eutrophic habitats, a relatively high chloride content and a fairly considerable specific conductivity. It thrives in fresh water especially after pollution with substances of an inorganic nature, such as industrial wastes and fertilizers. In habitats with a low chloride content this species may be associated with Wolffia arrhiza.\nThe flat growth forms of L. gibba are either winterforms, young stages or forms of less favourable habitats, i.e. of relatively poor and of brackish waters.

Description: Tetramyxa parasitica Goebel. Deze schimmel, welke gewoonlijk gallen op Ruppia veroorzaakt, werd op enkele plaatsen in Zeeland waargenomen (Gorteria 1, no. 12, 1963, p. 138\xe2\x80\x94140) en bleek ook aanwezig te zijn in herbarium-materiaal, al in 1868 op Texel verzameld (Gorteria 1, no. 14, 1963, p. 164). In 1965 werden de gallen van Tetramyxa parasitica gevonden in het Balgzandkanaal bij Den Helder, op Ruppia maritima en op Zannichellia palustris, en in een brakwaterplas op de Boschplaat op Terschelling, op Ruppia spiralis.