青藏高原东南缘五种火绒草属植物的核型

Karyotypes of Five Leontopodium Species from the Southeastern Qinghai-Tibet Plateau, Southwest China

报道我国青藏高原东南缘5种6个居群火绒草属植物的染色体数目和核型。银叶火绒草Leontopodium souliei 2n=2x=24=13M+8m+3sm,1B;坚杆火绒草L.franchetii 2n=2x=26=6M+18m+2sm,2A;华火绒草L.sinense;四川木里海拔2406m的居群:2n=2x=26=4M+22m,1B,四川木里海拔3074m居群:2n=4x=52=16M+36m,1B;美头火绒草L.calocephalum 2n=4x=48=3M+43m+2sm,1B;毛香火绒草L.stracheyi 2n=4x=48=13M+35m,1A。对现有的染色体资料分析表明:火绒草属的染色体核型比较对称,但种间具一定的变异;多倍化可能是该属在我国青藏高原及其周边地区发生强烈物种分化的重要原因之一。

The chromosome numbers and karyotypes of five species of the genus Leontopodium （Asteraceae） from Southeastern Qinghai-Tibet Plateau, Southwest China were investigated. Three species were studied karyomorpholog- ieally and reported for the first time ： L. franchetii 2n = 2x = 26 = 6M＋ 18m＋2sm, 2A ; L. calocephalum 2n = 4x = 48 = 3M＋43m＋2sm, 1B; L. stracheyi 2n=4x=48= 13M＋35m, 1A. Two species L. souliei and L. sinense presented dif- ferent chromosome numbers and karyotypes from the previous reports, that is, L. souliei 2n = 2x = 24 = 13 M ＋ 8m＋ 3sm, 1B; L. sinense, the population collected at altitude 2 406 m a.s.1. Muli County, Sichuan Province： 2n=2x= 26 = 4M＋22m, 1 B, the population collected at altitude 3 074 m a. s. 1. Muli County, Sichuan Province ： 2n = 4x = 52 = 16M＋36m, 1B. The comparison of existent chromosomal data indicates that Leontopodium is a genus with symme- try karyotype, but diversified obviously among different species. Polyploidization might have played an important role in the speeiation and evolution of Leontopodium on the Qinghai-Tibet Plateau and its southeastern peripher- al regions.