AbstractJiangsu Province is located along the lower reaches of the Yangtze River in the northern part of the subtropical zone. Its plain has been cultivated , and the hilly and mountainous land makes up 15 % of the total area , and its great majority is widely brought under cultivation with artificial forests and woody economic crops such as Phyllostachys pubescens , Camellia sinensis , Castanea mollissima , Cunninghamia lanceolata and Pinus massoniana ,etc. Natural vegetation is formed by deciduous broad-leaved forest that contains evergreen broad-leaved elements , which can be found only in the ridge of some hills and the fringe of some gullies , and have been classified as a framentational distribution type. There are 17 species of rare and endangered plants in Jiangsu. Of them , Parrotia subaequalis , Magnolia zenii , Magnolia ameona , Pseudolarix amabilis , Changnienia amoena , Ulmus chenmoui , Glehnia littoralis and Cinnamomum camphora are distributed in sporadic area and have become rare. Sinojackia xylocarpa , Emmenopterys henryi , Isotes sinensis and Ceratopteris thalict roides were found in some areas , but seemed extinct in recent years. Because of over- utilization , the habitats of Pteroceltis tatarinowii , Zelkova schneideriana and Changium smyrnioides have been rapidly deteriorated. B rachystachyum densif lorum and Glycine soja have often been found in their suitable habitats. These species are classified into 16 genera of 13 families. Of them , the antique floristic elements — Parrotia , Changium , Sinojackia , Emmenopterys , Pseudolarix , Pteroceltis , Glehnia and Changnienia are monotypic genera or oligotypic genera with an isolated position in phylogenies. Most of the rare and endangered plants are distributed in the south of Jiangsu , while some of them , such as Emmenopterys henryi , Pseudolarix amabilis and Magnolia ameona , are located on the northern fringe of their distribution area. The habitat fragmentation caused by human activities , the edge-effects of their marginal distribution and human destruction have synthetically led to the degeneration of primary habitats , reduction of population sizes and endangerment of these species.