Chromosome Studies in Cyperaceae, IV

Chromosome number of Carex species

Abstract

The chromosome numbers of 32 species and 3 varieties of the genus Carex have been reported. Five haploid numbers, 6, 8, 12, 13 and 17 are newly added to the series of known chromosome numbers of this genus, hence we have the total of 33 different haploid chromosome numbers, namely, 6, 8, 9, 12, 13, 15, 16, 17, 18, 19, every number of 23-43, 54 and 56.
The karyotypes of Carex siderosticta, C. lasiolepis, C. oxyandra and C. Reinii have been determined as follows, 1L^t+3L+2S, 3L+5S, 1 L^t+2L+4M+2S, 2L+7M+4S, respectively.
In 3 species aneuploid chromosome numbers have been found, i.e. in Carex gibba 2n=34 and 36, in C. breviculmis n=34 and 2n=64 and in C. conica 2n=34, 35 and 38. The ployploid relation has also been found in a single species, C. siderosticta, and also in the subsection Mitratae.
From the fact that artificial species hybrids have been obtained in 19 combinations (37.3% of all crosses actually made) of 13 species, it is suggested that natural hybridization may often occur and it must have a relation to the considerable extent to the origin of aneuploidy which is too complex to interpret satisfactorily in this genus.
Here the writer wishes to record his cordial thanks to Prof. Y. Sinotô under whose direction the work has been carried out. Thanks are also due to Dr. S. Akiyama, Dr. H. Hara, Dr. F. Maekawa who kindly identified most of the plants used, and to Dr. Ohwi who had interest in the present work.