Abstract: Quercus subg. Cyclobalanopsis(Oerst.) Schneid. is an important constituent of broad leaved evergreen forests in subtropical and tropical regions of Asia. It contains 122 species distrbuted primarily within the Tropical Asia (Indo-Malaysia) phytogeographic province. A number of species were analyzed to develop a biogeographical and phytogenetic context for the diversity within subg. Cyclobalanopsis. Southern China and the north northern part of the Indo-Chine Peninsula show the highest species diversity and may be considered the two centers of diversity. A number of species in Malaysia were observed to have some plesiomorphic characters, and this region may be considered the center of origin and a key area of endemism. On the island of Borneo, the area of Kalimantan is richest in endemic species and the fossil species record resemble this fact. In contrast, the endemic species from Hainan and Taiwan are more derived. The endemic species of Yunnan represent a mixture of neoendemics and paleoendemics. The formation of patterns of endemism in Cyclobalanopsis is due primarily to geographical isolation and the complex history of climatic and geological changes. Also we have discussed vicariance of Cyclobalanopsis: Q.glauca & Q.schottkyana, Q.gilva & Q.delavayi, Q.sessifolia & Q.augustinii are vicariance species between Sino-Japan and Sino-Himalaya.

Key words: Quercus subg. Cyclobalanopsis