Abstract: In this paper, the bioecological characteristics of 7 populations of Allium wallichii in Jizu Mountain were systmatically analyzed. There were diploid 2n= 2x= 14) and tetraploid (2n=4x=28) observed in the species Allium unllichii Kunth in Jizu Mountain. The habitats of diploid population are constant and barrener, which restricts the intrusion of tetraploid plants. No obvious differentiation existed between diploid population. Tetraploid populations' habitats are various, and the differentiation in niche, morphology and phenology between the population are significant. The diploid plants can't stand the shortage of light in forest, however, on the grassland and the rocks, the dwarf diploid plants have no capacity to compete with tetraploid plants and grass, so the diploid also couldn't intrude into the habitats of tetraploid plants. The dominant ecological factors causing population differentiation are light, soil and biotic factors. However,the water factor is the restricted factor which is the distributing underline of Allium wallichii in Jizu Mountain.

Key words: Jizu Mountain