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Medientyp:
E-Artikel
Titel:
Chromosome Numbers in American Polygonatum Species
Beteiligte:
Therman, Eeva
Erschienen:
American Botanical Society, 1950
Erschienen in:American Journal of Botany
Sprache:
Englisch
ISSN:
0002-9122;
1537-2197
Entstehung:
Anmerkungen:
Beschreibung:
<p>The chromosome numbers in fifteen North American Polygonatum strains belonging to the species P. cobrense, P. pubescens, P. biflorum, and P. commutatum have been determined. Of these P. cobrense was diploid with 2n=20 chromosomes, while the three latter species contained both diploids with 2n=20 and tetraploids with 2n=40 chromosomes. In addition in P. commutatum a hexaploid strain with 2n=60 chromosomes was found. The chromosome morphology was analyzed from somatic root tip plates. It could be established that all the diploid strains were identical as to their chromosome morphology with five long pairs, four short ones, and one pair of intermediate length. Two of the longer chromosome pairs are provided with secondary constrictions. The meiotic divisions in the three diploids, as well as in the tetraploid, were quite regular, with only bivalents being formed. The taxonomical difficulties encountered in this group are partly explained by the occurrence of tetraploidy and hexaploidy. The polyploidy must have originated independently in the different strains. The conclusion can be drawn that future taxonomic studies on American Polygonatum species must inevitably be based on cytological investigation if reliable results are to be obtained.</p>