Abstract: Sixty-one bamboo species belonging to twenty-three genera in Yunnan which had been in flowering and fruit bearing in past fifteen years were recorded in this paper.The study shows for the first time that the flowering and fruit bearing phenomena of bamboos closely relate to their living states,wild or cultivated,and also are connected with their taxonomical position in genus level.The main points are as follows.(1)Around 88% wild bamboo species are in the type of flowering wholly.On the contrary,64% cultivated bamboo species are in the type of flowering fragmentarily.(2)Furthermore,the most bamboo species in the genera of Melocalamus,Schizostachyum,Cephalostachyum, Gigantochloa,Indosasa,Ampelocalamus act.are in the type of flowering wholly,and the most bamboo species in the genera of Bambusa,Dedrocalamus,Neosinocalamus,Pseudostachyum act.are in the type of flowering fragmentarily.(3)The most species in the genera Melocalamus,Schizostachyum,Gigantochloa,Cephalostachyum,Ampelocalamus act.are dead after flowering.And those in Neomicrocalamus,Bambusa,Indosasa act.are deadless after flowering.(4)About 79% wild bamboo species could bear fruits after flowering,only 27% in cultivated species.It means that most wild bamboo species can reproduce naturally by seeds,and most cultivated bamboo species have lost their ability to multiply by sexsual reproduction.The authors here try to explain the flowering phenomena of bamboo in the viewpoint-Environment-Endopathic Presumpution.It is considered that bamboo will flower when they grow to physiological maturity.The evironmental factors could affect the course of bamboo flowering,such as advancing,delaying or terminating the flowering.The this kind of effect,however,can only occur in the period during which bamboo has almost developed to physiological maturity.

Key words: Yunnan, Bamboo, Flowering, Environment-endopathic presumpution