慈姑花的开放式样及其花粉流

Floral Display and Pollen Flow in a Natural Population of Sagittaria trifolia 

对一野生慈姑（ＳａｇｉｔａｒｉａｔｒｉｆｏｌｉａＬ．）居群的性表达状态及其花粉流散布规律进行了观测。慈姑雌雄同株，单株雄花数是雌花数的３．６倍。雌雄花单花期均为１ｄ，但二者开放式样不同。尽管雌花的数目较少，但在１ｄ内开放较多的花，其花的开放速率比雄花快。在居群水平上表现出雌雄花比例随时间大幅度波动。在传粉者进行的２６１２次访花活动中，传粉者表现出偏“雌性”访问，对每朵雌花的访问是雄花的１．４倍。用番红染色法标记慈姑的花粉运动表明，花的不同开放式样影响花粉流的散布。当雄花数占高比例时，花粉主要在邻近的个体间散布；而雄花的比例较低、雌花相对较多时，花粉远距离散布的强度加大。

The relationships between sex expression, pollinators response and pollen flow in a field population of Sagittaria trifolia L. were examined. These plants were monoecious with the number of male flowers 3.6 times of female flowers. The anthesis of two sexes was only one day, but the floral display was different. The female flowers opened firstly and bloomed more flowers in one day in a raceme; however, the male flowers opened few flowers in one day and lasted longer time in bloom. The floral display thus appeared large fluctuation at the daily ratio of two sexual flowers in the population. In 2612 pollination activities, the pollinators tended to visit female flowers. The mean number of visits received per female flower was 1.4 fold than that of per male flower. To test effect of the different floral display on pollen flow, the authors estimated pollen dispersion by labeling the anthers of male flowers with safranine dye in two experiments. When the male flowers were more abundant, most dyed pollen dispersed close to the labeled plant. As the female flowers having relatively high proportion in the population, the labeled pollen grains moved in far distance.