In the present study, the somatic chromosome numbers of about 40 species of the genus Carex have been determined (Table 1). In this Table the chromosome numbers are arranged in the systematic order adopted by Kükenthal. Twenty different chromosome numbers have been found as follows, 30, 34, 36, 38, 42, 48, 52, 54, 56, 60, 62, 64, 66, 68, 70, 74, 76, 78, 84 and 90 (Figs. 1-39). These numbers cannot be generally arranged in a series of multiples, but it is noteworthy that the polyploid relation has been observed in C. multifolia and C. stenantha, namely, 2n=30 and 60 in the former (Figs. 18-19), 2n=34 and 68 in the latter (Figs. 27-28) and that aneuploidy has also been found in C. conica, 2n=34, 38 and 42 (Figs. 16-17). As a rule, the chromosome shape is spherical or elliptical. And the chromosome decreases generally in size as their number increases. In C. pilosa, two individuals having the different chromosome numbers (n=32 and 57) have been detected and it is a very interesting fact that their meiotic chromosomes show the secondary association of different types, namely, in the individual of 32 chromosomes, each two bivalents associate generally with each other and in that of 57 chromosomes, each three bivalents associate together (Figs. 44-45). Such pairing in the genus Carex has not been hitherto reported by any investigator.
