Abstract: Observations on flowering biological characteristics in 21 bamboo species within 6 genera have been made for more than 10 years in Anjie Bamboo Botanic Garden.The results were as follows:Some bamboo species formed blossom bud and flowered in the same year,some formed such bud in one year and flowered in the subsequent year.The blossom period of different bamboo species varied,which might be divided into two kinds,i.e.long blossom period and short blossom period.There was considerable variation in flowering performance of 21 bamboo species.When refer to the twigs bearing the flower,it might be divided into two types,one with leaves and another without leaves,and when refer to the location and time of flower generation,primary flowers and secondary flowers could be recognized.In Phyllostachys iridenscens and Ph.bambusoides,it took the anthers about 48 hours from protrusion to splitting,and for the stigmas from protrusion to withering less than 24 hours.The growth of the flowers was closely related to the weather conditions.The fruiting percentage of bamboo plants was generally low or even zero.Phyllostachys iridenscens as a species with higher fruitage ability,had a record of fruiting percentage of 6.1%.The anatomical results showed that high percentage of sterility was due to the withering of ovary and anther or insect damage in Pleioblastus amarus and other 7 bamboo species.77.7% of 337 flowers observed,were unfruitful.