A Study on the Flora of the Seed Plants from Zigui County of the Three-Gorge Reservoir Area

Zigui is the first county situated in the upper reaches of the dam in the Three-Gorge Reservoir Area.The following characteristics were found in the study of the flora of the seed plants in this county:It is abundant in wild species,containing 1662 species of seed plants which belong to 703 genera and 138 families.Dominance phenomenon is obvious.The flora is archaic,relic and pristine;Single-species and few-species genera are rich.The types of distribution are various and geographical elements are complex,and dominance of temperate elements is obvious and subtropical elements are plentiful.It has much in common with tropical flora,and shows some transitional nature.Endemism is notable,according to the statistics in the levels of species and genera;this flora has the most abundant common endemic species with that of Sichuan Province.It is closely related with the provinces of the floristic region of Central China,so it is consistent with the opinion that Eastern Sichuan and Western Hubei Province is one of the three endemic centers,and also supports Wu Zhengyi's opinion on the partition of the floristic region of Central China.