关键词: 紫背天葵, 花部特征, 繁育系统, 杂交指数, 濒危原因

Abstract: By investigating on the specific field observation and breeding cultivation of endangered
plant（Begonia fimbristipula Hance），its outcrossing index，pollen vitality and stigma receptivity，the ratio
of pollen and ovule，artificial pollination and bagging experiments were performed for understanding the
flower feature，blossom dynamic and breeding system. Results showed：The single plant florescence of B.
fimbristipula is 25–30 d，while group plants florescence last to 45–55 d. The flowers，setting on the
same inflorescence，are monoecism. Male and female flowers mature at different time，the stamens mature
earlier than pistils，and the distance between anther and stigma is about 2.0 cm. The blooming pattern
follows male-female-male；Female flowers lag 2–3 days than male ones. The out cross index（OCI）is ≥
4，pollen-ovule ratio（P/O）is 96.56. Taking the results of the emasculated，bagged and artificial pollination
experiment together ， it indicates that B. fimbristipula flower is a mixed-crossing system using
self-compatibility as the main breeding form and concomitance out-crossing. The specific dependence on
its living environment and the long term of small gregarious self-compatibility might be one of the reasons
causing this species in endangered，“bulb”is an effective way to its reproductive compensation.

Key words: Begonia fimbristipula Hance, floral syndrome, breeding system, crossing-breeding
index, endangered cause