Flora Of Spermatophyte In The Xiangxi Tujia And Miao Autonomous Prefecture

Located at the junction of Hunan,Hubei and Chongqing,Xiangxi Tujia and Miao Autonomous Prefecture nears the plant refuge of "East Sichuan-Western Hubei Area" and belongs to the transition zone between the second and third opography stairs of China(Line of Wushan and Xuefeng Mountains).Although this region has great research value,there is no comprehensive study on the flora of spermatophyte.To explore this flora,the related data from specimens(included 25236 specimems in total)in the herbarium,literatures,and field investigations have been comprehensively compiled in this work.Then,the Areal-type of families and genera,characteristics of endemic,ancient and transition,position of this flora,and doubted species in this flora had been studied and discussed.The main results are as followsTotally,2457 species(included subspecies and variants)of wild spermatophyte belonging to 164 families and 856 genera,including 15 species of gymnosperms belonging to 7 families,12 genera,and 2442 species of angiosperms belonging to 157 families,844 genera,are distributed in this region.Among them,Asteraceae,Poaceae,Rosaceae,Fabaceae,Lamiaceae,etc.are the species-richest families,and Rubus,Carex,Polygonum,Clematis,Ilex,etc.are the species-richest genera.The floristic compositions of spermatophyte in this region are diverse with transitional and tropical kinship.Firstly,the tropical families are more than the temperate families.164 families are divided into 12 Areal-type.Among them,69 families are tropical and account for 58.47%of non-cosmopolitan families,represented by Lauraceae,Magnoliaceae,Urticaceae,Euphorbiaceae,etc.,49 families are temperate and account for 41.53%of non-cosmopolitan families,represented by Liliaceae,Fagaceae,Aceraceae,Berberidaceae,etc..Secondly,the temperate genera are more than the tropical genera.856 genera are divided into 14 Areal-type.Among them,431 genera are temperate and account for 54.90%of non-cosmopolitan genera,represented by Quercus,Rhododendron,Acer,Viburnum,etc.,354 genera are tropical and account for 45.10%of non-cosmopolitan genera,represented by Ficus,Caesalpinia,Zanthoxylum,Ilex,etc..The flora of spermatophyte is archaic with many relict groups endemic in China.2 relict and single families endemic in China of Eucommiaceae and Ginkgoaceae are included.38 genera endemic in China are found,many of which are ancient and relict,such as Metasequoia,Cunninghamia,Pinus,Ginkgo,Chimonanthus,Davidia,Eucommia.The flora of the spermatophyte should belong to the East Asia Region,China-Japan forest Subregion,Central China Province,Sichuan-Hubei-Hunan Subprovince,with representative families such as Eucommiaceae,Ginkgoaceae,Stachyuraceae,Actinidiaceae,Cercidiphyllaceae,and representative genera such as Quercus,Metasequoia,Eucommia,Sargentodoxa,Eomecon,and with highest similarity coefficient of the genera to Hupingshan,Jinfoshan,and Shennongjia,where belong to the Central China Province,and share many Chinese endemic species with Hubei,Sichuan and Guizhou of Central China Province.In addition,this flora is closely related to the East China Province.In this floristic research,a new species of Lysimachia xiangxiensis,and a new record of geographically discontinuous distribution of Diospyros zhejiangensis were found.Additionally,phylogenetic location of an uncertain taxon has been determined,which is named as Citrus ×centrochinensis.These species have enriched the floristic data in this area and they are of great significance in research of Floristic Phytogeography.