De Salicornia-soorten van Zuidwest-Nederland

Morphological and cytogenetic variations in S. brachystachya (G.F.W. Meyer) König and S. dolichostachya Moss were studied in some of Salicornia populations in the southwestern part of the Netherlands (fig. 1). Compared with Flora Europaea the first species includes those of the S. europaea group, whereas the latter species includes those of the S. procumbens group. The following morphological characters were studied: the dry seeds (fig. 2, table 1), the cotyledons (fig. 3, table 2), the stem internodes (fig. 4, table 3), the inflorescences (fig. 5, table 4), colour and succulence, the rooting system (fig. 6), the flower ratio (fig. 7a, 8), the segment ratio (fig. 8), the stem diameter (fig. 7b, 8). The species show a considerable overlap in all these characters, except in cotyledon fusion and two inflorescence characters. Chromosomes from root tips of 65 plants were counted. All plants of S. brachystachya were diploid (2n = 18), all of S. dolichostachya were tetraploid (2n = 36). Seedlings of five tetraploid plants erroneously pre-identified as S. brachystachya proved to belong to Sdolichostachya both cytologically and morphologically. The most reliable morphological character for the identification of the two species is the length of the anthers: in S. brachystachya 0,25 – 0,45 mm, in S. dolichostachya 0,50 – 0,77 mm. These differences strictly coincide with the level of ploidy. In the first species flowers have usually one, rarely two stamens; in the latter species one or two stamens. Fig. 8 gives a summary of the comparison of a number of morphological characters of diploid (black dots) and tetraploid (circles) plants. It is concluded that both seedlings and flowering or fruiting plants can be identified reasonably well on morphological grounds; only in the intervening period identification remains uncertain. Finally some infraspecific forms of S. brachystachya are recorded for the South-west Netherlands: a form with slender and often drooping terminal segments (‘subsp. gracilis G.F.W. Meyer’ of König, 1960), and a procumbent form (‘f. prostrata Pallas’).