Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan.
Am J Bot. 2002 Mar;89(3):441-6. doi: 10.3732/ajb.89.3.441.
We analyzed the effects of temporal variation in floral display size (number of flowers open at one time on a plant) on the rate of pollen removed and receipt of individual flowers for the sequential blooming plant Narthecium asiaticum (Liliaceae). Because of the acropetal blooming of this species, the display sizes when upper flowers opened was much greater than the display sizes when lower flowers opened. Our experiments revealed that large displays lead to a high rate of pollen removal from individual flowers, though they do not lead to a high rate of ovule fertilization. Consequently, the rate of pollen grains removed per flower by pollinators was greater in upper flowers than in lower flowers. The pattern of sex allocation in individual flowers within a raceme was consistent with such variation. Namely, both maleness [stamen mass/(stamen mass + pistil mass)] and pollen : ovule ratio were larger in upper flowers. We suggest that the temporal variation in display size, in addition to such factors as dichogamy and pollinator directionality, also produces variation in the probability of successful pollen transfer from individual flowers that may cause the variation in the sex allocation of individual flowers.
我们分析了花展大小（一朵植物一次开放的花朵数量）的时间变化对个体花的花粉去除率和接收率的影响，花展大小为顺序开花植物贝母（百合科）。由于该物种的向顶开花，当上部花朵开放时的展示尺寸远大于下部花朵开放时的展示尺寸。我们的实验表明，大的展示会导致个体花朵的花粉去除率很高，但不会导致胚珠受精率很高。因此，传粉者从每朵花上移除的花粉粒数在上部花朵中比在下部花朵中更多。一朵花在花序中的性别分配模式与这种变化一致。即，上部花朵的雄性（雄蕊质量/（雄蕊质量+雌蕊质量））和花粉：胚珠比都更大。我们认为，展示尺寸的时间变化，除了二型性和传粉者方向性等因素外，还会导致个体花朵成功花粉转移的可能性发生变化，这可能导致个体花朵的性别分配发生变化。
