In:
Canadian Journal of Botany, Canadian Science Publishing, Vol. 35, No. 5 ( 1957-09-01), p. 715-761
Abstract:
The small section Capillares of the genus Carex has been studied from the cytological and taxonomical points of view. It comprises nine distinct species, one of which (C. Boecheriana) is raised to specific status in this paper. Three species include two distinct subspecies each; two varieties and three formae are accepted for two species respectively. The chromosome numbers of the taxa involved are 2n = 18, 36, 38, 40, 54, 56, and 58. It is pointed out that the chromosomes of Carex have a polycentric or diffuse kinetochore and that this explains the aneuploid variations in number known to be typical of the genus. Karyotypic analysis of the chromosome complements of the section Capillares revealed that in the basic diploid set of 2n = 18 chromosomes four units are long, 10 are medium and about half the length of the long ones, while four are small and about half the length of the medium ones. This frequency of size classes is also met with in the plants with 2n = 36 and 54 chromosomes. Those taxa with 2n = 38, 40, 56, and 58 chromosomes show, however, such a deviation in the frequency of the size classes that it seems logical that these numbers have been produced by a secondary fragmentation of the chromosomes. On the basis of karyotypic analysis of this section and other groups of the genus it is concluded that the primary basic number for the genus Carex in particular and the family Cyperaceae in general must have been x = 5, all other numbers having been derived mainly by fragmentation of chromosomes with a polycentric or diffuse kinetochore. This phenomenon of partial agmatoploidy is widespread in Cyperaceae, whereas complete agmatoploidy is typical of the closely related Juncaceae.
Type of Medium:
Online Resource
ISSN:
0008-4026
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1957
detail.hit.zdb_id:
218116-2
detail.hit.zdb_id:
1481926-0
SSG:
12
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