Cytological Studies on the Tribe Helianthoideae (Asteraceae)

Cytological investigations on 7 taxa of the tribe Helianthoideae (Asteraceae) reveal certain interesting features. Meiotic counts reported here are all normal, forming regular bivalents. Karyotypes show homogeneity with graded types of chromosome complement. The occurrence of tetraploid species of Tridax procumbens L. (n = 18) is of interest. The reports of Eclipta alba (L.) Hassk. (n = 11, 2n = 22), Tathonia tagetiflora Desf. ex Juss. (n=17), Xanthium strumarium L. (n = 18) are confirmatory nature. Aneuploid variations are also noted in some cases.