Synopsis of the Chinese species of Begonia (Begoniaceae), with a reappraisal of sectional delimitation

Abstract

Nine sections of Begonia are recognized and illustrated based on the 150 species known from the Chinese region. They are sect. Coelocentrum Irmsch., sect. Petermannia (Klotzsch) A. DC., sect. Alicida C.B. Clarke, sect. Diploclinium (Wight) A. DC., sect. Reichenheimia (Klotzsch) A. DC., sect. Parvibegonia A. DC., sect. Platycentrum (Klotzsch) A. DC., sect. Sphenanthera (Hassk.) Warb. and sect. Leprosae (T.C. Ku) Y.M. Shui (combination made here). Section Leprosae is characterized by the trilocular, wingless, clavate, berry-like fruits. Based on a detailed analysis of fruits and placentae, the sectional placement of many species of Chinese Begonia is realigned. Relationships among the sections are discussed: sect. Coelocentrum is likely to represent one of the most ancient groups in the genus Begonia; sect. Diploclinium, a complex group, is related to several sections; sect. Sphenanthera is an entomochoric and entomophilous group; sect. Leprosae is intermediate between sections Sphenanthera and Diploclinium. Begonia tessaricarpa C.B. Clarke (sect. Sphenanthera), from Xizang, is documented here as a new record for China.