Studies on South Indian Compositae
II. Cytology of the genus Vernonia Schreb
1976 年 41 巻 2 号 p. 401-406
詳細
1976 年 41 巻 2 号 p. 401-406
Cytology of ten species of Vernonia indigenous to South India has been studied, viz. V. beddomei (n=9 and 2n=18); V. cineria (n=9 and 2n=18); V. divergens (n=9 and 2n=18); V. conyzoides (n=9 and 2n=18); V. albicans (n=9); V. penin-sularis (n=9); V. indica (n=18); V. anthelmintica (n=10 and 2n=20); V. bourneana (n=10 and 2n=20) and V. elaeagnifolia (n=20 and 2n=40).
Chromosome records show that the Indian members of the genus fall under two basic series, x=9 and 10, of which the former group shows greater preponderance. The x=10 species are considered to be the earlier evolved ones and those with x=9 diploid species are suggested to be aneuploid derivatives.
Polyploid frequency is very low in the genus. V. indica and V. elaeagnifolia reported here are the only polyploids so far known, both being allotetraploids.
Karyotype study is made for the first time in this genus. Data of karyomorpho-logy on seven species indicate that the karyotypes of the diploid species are unspeci-alized and it appears that factors resulting in karyotypic specialization have not been significantly operative in the evolution of species of Vernonia.
