Abstract: Psammochloa villosa (Trin.) Bor (Gramineae) is a rhizomatous grass with characteristic sand fixation. Ten enzymes encoded with 15 allozymic loci were used to examine the genetic structures of four natural populations in Inner Mongolia from different habitats. Electrophoretie data indicated that P. viUosa had lower genetic variation (He = 0.104) and lower clonal diversity (D = 0.764) than other similar plants. Genetic compositions of the 4 populations were different. In Shilongmiao mobile dune and Shihuimiao fixed dune there were more genotypes and higher levels of variation than in Shilongndao fixed dune and Shihuimiao semi-mobile dune. Just hke other clonal plants, most genetic variation of P. villosa resided among populations ( Gst = 62,16% ). Most genotypes were local, and there were no spread genotypes. Factors contributed to the genetic structure are herein discussed.

Key words: Psammochloa villosa, Clonal plant, Allozyme, Population genetic structure, Clonal diversity