Taking 6 varieties as test material，this paper studied on characteristics of floral organ
morphology，population florescence，flowering dynamics of a single flower，flowering time of different types
of flower，stigma receptivity，pollen viability，outcrossing index and pollination pattern of water caltrop．
The results showed that water caltrop flower was solitary and bisexual．A single flower can bloom for 15 h．
The population florescence starts from May to October and full bloom stage is July to August．Different types
of water caltrop cultivar have different flowering peaks within a day．The period for stigma to receive pollen
is mainly within 2 h after the sepal cracked，and the seed set rate can reach over 50%．Pollen viability can
be maintained for 7.5 h under natural conditions．The water caltrop is mainly self-pollinated，and also exists
partly apomixes and a small quantity of cross-pollination．