The Research On Seed Plants Flora Of Liangjiang Canyon In Chengbu County, Hunan

The Liangjiang canyon is situated in southwestern Chengbu Miao Autonomous County,Hunan province,extending from 25°8'～26°42'N, 109°58'～110°37'E,with an area 54 km2.Based on the exploration,this paper discuss the floristic structure of ferns,families,genera and species of seed plants,as well as features Liangjiang canyon flora.1.The quantity composition of Liangjiang canyon flora There are 167 families,683 genera and 1594 speciea are recorded in the area,of those families,genera and species recorded in Liangjiang canyon,there are 7 families,10 gengera and 18 species in Gymnospermae,138 families,550 genera and 1386 species in Dicotyledones,22 families,123 genera and 208 species in Monecotyledones.2.Consistence of families of seed plants There are 167 families in Liangjiang canyon flora,including 7 families of Gymnosperm.The families can be grouped into 11 areal-types and 5 subtypes as proposed by Wu Zhengyi.Of the 11 types,Pantropic type and its subtypes with 55 families is at the first position. Next are Worldspread type with 47 families and East Asian type with 30 families.There are 4 families endemic to China.3.Genera of Liangjiang canyon In Liangjiang canyon flora,there are 683 genera.Analysis shows that (1) The genera can be grouped into 13 areal-types and 13 subtypes as proposed by Wu Zhengyi.(2) Of the 13 types,Pantropic type with 115 genera is at the first position.Next are Noth temperate type with 114 genera and East Asian type with 100 genera.(3) The total number of genera belonging to various temperate types comes to 317 and that for tropical and subtropical types is 290.R/T ratio (tropical genera/temperate genera) is 0.92,so,in this flora,Temperate element is more important than other element.4.Study on species of Liangjiang canyon of Seed plant There are 1594 species of seed plants recorded in Liangjiang canyon,these species can be grouped into 14 areal-types,among them Chinese Endemic species with 740 species is at the first position,the following next are East Asia Endemic species with 326 species,Tropical Asia species with 210 species.5.Endemic to Liangjiang canyon flora In Liangjiang canyon,4 families,24 genera,740 species are endemic to China.740 species are classified into 15 subtypes.6.Relation with its neighboring regions The flora is much more closely allied to Yunshan than to the other of its neighborhood,it belongs to Center-China Province,Holartic Kingdom.7.New taxon 1 new specie is described,4 species are reported as new records to the flora of Hunan Province,there are Chionanthus guangxiensis, Disporum uniflorum, Calanthe aristulifera, Goodyera kwangtungensis.