Abstract: Ex situ conservation is regarded as an important supplementary means to prevent species extinction.To effectively conserve and manage the ex situ population of an endangered species(Psilopeganum sinense)in Wuhan Botanical Garden(WBG),we examined floral biology,breeding system and pollination process by conducting field observations,pollen activity and stigma receptivity examinations,and artificial pollination experiments.The flower was protandrous and the life span of a single flower was approximately 6-8 days.The sex expression of a single flower experienced male phrase,bisexual phrase and female phrase.Bag experiments indicated no apomixes and no wind pollination,but spontaneous autogamy.Our experiments confirmed the type of breeding system was facultative xenogamy.The effective pollinators in WBG were three species of hover flies(Eristalis cerealis,Sphaerophoria sp.and Episyrphus balteatus)and two species of bee(Halictidae),which were the same as the pollinators in natural populations of Yichang.The fruit set was 90% in open pollination treatments in WBG,suggesting no reproductive barrier in the ex situ environment.Spontaneous autogamy and facultative xenogamy showed Psilopeganum sinense has the potential to adapt to habitat fragmentation and disturbance.