Chromosome Studies in the Genus Carex, with Special Reference to Aneuploidy and Polyploidy

抄録

The chromosome configuration at the IMs of the intraspecific hybrid of Carex oxyandra (n=9)×(n=10), C. gibba (n=18)X×(n=17), and C. parciflora (n=19)×(n=22), is described. The pattern of the chromosome configuration at the first meiotic metaphases in the first two case, is characterised by the formation of a heteromorphic association of trivalent. The duplicated C chromosome in these hybrids is considered as a sort of extra chromosome. Similar karyological condition prevails in the Carex and its significance to the production of the aneuploidy in this genus is discussed.
The chromosome configuration observed at the IMs of the intraspecific hybrids of C. parciflora is complicated. An analysis of the data of two sister plants, C63-4 and C63-2, has disclosed the previously undisclosed structural hybridity, i.e. the allopolyploid nature of this species, to some extents. In this connection, a subject of lengthy study and discussion, i.e. the aneuploidy and polyploidy in the genus Carex, is discussed. From the available data, the following conclusions are offered: The aneuploidy in the chromosome numbers in this genus is produced through the cross, among the aneuploid plants with a high degree of polyploidy as well as through the irregularities of the chromosome behaviour at meiosis caused by the structural hybridity which is due to the polyploid nature of species. The basic number in the chromosomes of the genus Carex is of rather small than those postulated heretofore and a considerable number of species are the secondary balanced polyploid.