Studies on the Geographical Distribution and Floristic Characteristics of the Genus of Dryopteris Adanson from Hubei,China

This paper deals with the geographical distribution and the floristic characteristics of the genus of Dryopter is from Hubei Province of China.Dryopteris is commonly distributed in the world.One center of distribution and diversity is in southwest China and the east Himalayan,another in Japan,southeast and south China.Dryopteris is a very natural northern temperate genus.In China,including 134 species (7 varieties),more than 80% of Dryopteris are distributed in southwest China (i.e.Yunnan,Sichuan,and Guizhou).Floristic analysis indicates that,there are 36 species of Dryopteris in Hubei,which account for 26.87% of all the species of this genus in China.They are mainly distributed in the northwest and southwest of Hubei.Dryopteris is one of the main components of the herb layer in the forests of Hubei.In Hubei the geographical elements of the species are complex.Among them,both Sino-Japan and Chinese endemic elements are dominant,which account for 37.84% and 30.56% of all the species of this genus,respectively.The floristic characteristics of the east of Hubei differ greatly from those of the west.Namely, east Hubei belongs to east-China flora,which shows the characteristics of the transition from warm temperate zones to subtropical zones.West Hubei belongs to the central China flora,which is abundant in species,and is closely related to the southwest China flora.The flora of Dryopteris in Hubei is closely related to its neighbor regions including Sichuan,Yunnan,Guizhou,Jiangxi and Zhejiang.And the similarity coefficients are 77.78%,70.27%,67.57%,62.16%,and 62.16%,respectively.The floristic characteristics show distinct transitional nature.It acts as a link flora between east-China flora and central China-flora.