Abstract: According to the population biology theories, genetic diversity of 35 populations of Agropyron mongoliucm Keng distributed over various regions in China was studied. The results showed that there was an abundant genetic diversity (H'=1.7779) among these populations in morphological characters. As for the distribution pattern of genetic diversity, the genetic variation among populations (90.85 %) was greater than that within populations (9.15%). Genetic diversity of this species distributed over every region was different, whose turn was Shaanxi region (H'=1.8627) > Ningxia region (H'=1.1.8332) > Inner Mongolia (H'=1.7232) > Xinjiang region (H'=1.6453) > Gansu region (H'=1.6436). But those of Shaanxi and Ningxia regions were collected from the southern brink of the Maowusu desert where there have abundant populations, which is about 68.6 % of the total analyzed. So high emphasis should be put on the Agropyron mongoliucm populations distributed over the southern brink of the Maowusu desert whether for the purpose of scientific research or productive application. Additionally, the significance of the population for species' definition and the effective conservation strategy to this plant were discussed.

Key words: Agropyron mongolicum Keng, Population biology, Genetic diversity, Morphology, Distribution center