A CLASSIFICATORY SYSTEM AND GEOGRAPHICAL DISTRIBUTION OF THE GENUS GYNOSTEMMA BL.(CUCURBITACEAE)
绞股蓝属植物的分类系统和分布

The genus Gynostemma consists of 16 species and 2 varieties, which fall into two subgenera and two sections, i. e. , Subgen. Trirostellum including two new sections, Sect. Pentagynae and Sect. Trirostellae, and Subgen. Gynostemma, The modern distribution centre of the genus ranges from drainage areas of the Yangtze River to Yunnan, southwest China. Northwards, it is distributed to the south slope of the Qinling Range and the south branch of the Huaihe River, eastwards through central-eastern China to Korea Peninsula and northern Japan; in the south, it extends to Indo-China, Malaysia, Philippines, Indonesia and Papua New Guinea, with the west limit of this genus found in northwestern India. The distribution pattern of the genus indicates a nature of Tropical Asia Type. Based on the above mentioned distribution pattern, the centre of diversification and the ecological adaptation of both primitive and advanced groups, also by means of palaeogeological, palaeogeo-graphical and palaeoclimatical evidence and the origin of its out group, the genus Gynostemma, together with its closely allied genera Hemsleya, Gomphogyne, etc. is considered to have originated on the Kham-Dian Oldland during the Early Tertiary.