Study on Genera Endemic to China in the Spermatophytic Flora of Chongqing

66genera endemic to China were found in the spermatophyte flora of Chongqing , including 100 species of 40families.The floristic characters are as follows :( 1 ) The differentiation degree of endemic elements varies in different major families of the seed plants.It has a large number of monotypic and oligo- typic genera , and riches in rare and endangered plants.Proportion of herbaceous endemic genera in Chongqing is lower than that in the whole nation.Most of the 66endemic genera are ancient and relic , but a certain number of young genera can also be found. ( 2 ) 22endemic genera are deciduous woody plants , occupying 73.33%of the total endemic woody plants in Chongqing.A majority of the endemic genera distribute in an area of 1 000-3 000malt. , showing an obvious temperate nature. ( 3 ) Areal-type analysis showed that the 66endemic genera could be divided into two subtypes , most of which were restricted in eastern to central China , while others were mainly endemic to southern China.Southeast and northeast Chongqing are two main distribution centers of the Chinese endemic genera in Chong-qing , while the midwest part also has a certain amount of endemic genera distributed.