Abstract: Seed plant diversity of screes of northwest Yunnan has been studied at present paper based on herbarium and literature records and field investigations.There are 519 seedplants found on the screes in northwest Yunnan.Those plants are grouped into 103 genera and 29 families.The arealtypes of genera have been analyzed.47.5% genera belong to the north temperate distribution pattern based on Wu's distribution pattern.And 56.8% species are endemic to China including 10.4% are endemic to northwest Yunnan.The ecoclimatic adaptation in both morphology and physiology of the scree plants was also investigated.Herbs are dominant in alpine screes including 421 perennial herbs.Low and trailing plant,rosette form,extreme low herb,and cluster plants,rhizoma,well developed fleshy or ligneous roots and dominant dehiscent fruits are the important characters of the typic alpine screes which demonstrate the well coevolution between the plants and environment.Meanwhile,the use of the plant resources on screes has been discussed.Some advices on conservation of the fragile ecosystem of alpine screes and using the plant resources properly has been suggested.

Key words: Seed plant diversity