裸蒴属的核型及三白草科四属间系统关系的探讨

本文首次报道三白草科裸蒴属中华裸蒴(Gymnotheca chinensis Decne)和白苞裸蒴(G. involucrata Pei)的染色体数目。两个种的体细胞染色体数均为2n=18,染色体基数为x=9。三白草科原始祖先的染色体基数假定为x=11,裸蒴属可能是经非整倍减少演变而来。裸蒴属间期核型属球状或棒状前染色体型。本文根据三白草科染色体研究的结果和现代地理分布格局,结合其他分枝学科的研究资料,对科下四属间的系统发育关系提出了初步假设。

KARYOMORPHOLOGY OF GYMNOTHECA AND PHYLOGENY OF FOUR GENERA IN SAURURACEAE

Both species of Gymnotheca (G. chinensis Decne, G. involucrata Pei) have the chromosome number 2n=18, the basic chromosome number x = 9, and show the round or rod-shape prochromosome at interphase. The original basic chromosome number of Saururaceae was presumed to be x = 11, in the genus Gymnotheca has an aniploid reduction basic chromosome number from x= 11 to x = 9. A phylogenetic scheme of four genera in Saururaceae according to the data from karyomorphology, basic chromosome number, palynology, embryology and floral vasculature, shows in Fig.l. Saururus is the most primitive genus in this family; Houttuynia seems to be the most advanced genus in Saururaceae; Anemopsis is the most specialized taxon of the family Saururaceae, which is adaptable to the alkaline places; Gymnotheca is relatively advanced compared to Saururus, it was reactivated during the Himalayan erogenic movement.