A PRELIMINARY STUDY ON THE PTERIDOFLORA IN XISHUANGBANNA LIMESTONE FOREST

Xishuangbanna is situated in the southern part of Yunnan Province and is contiguous to Loas and Burma. Accoding to the investigation and grasped data, up to now, 24 families, 52 genera and 127 species (include varieties) of Pteridophytes have been recorded in Xishuangbanna limestone forest. In which, the largest families and genera are Polypodiaceae, Pteridaceae, Aspleniaceae, Adiantaceae, Aspidiaceae and Pteris, Asplenium. Adiantum, Pyrrosia, Cyclosorus. Acording to the results of floristic analysis.this Pteridoflora has the tropical character of SE Asia. In the floristic composition of this forest the families of tropics and mainly tropics distribution make up 70% of the total families; the genera of tropics distribution make up 80% of the total, and the genera of tropics Asia make up 33. 3% of the total. Though the Pteridoflora in Xishuangbanna limestone hills have certain relationship with those of Guangdong and Guangxi, the coefficient of similarity is only 0. 32 on species; and many Pteridoflora components are occured in southwestern China, southern China or SE Asia of tropical Asia. There are no endemic families, genera and species in limestone hills of Xishuangbanna.