Relationships between pollen histochemistry, pollen grain number, ovule number and pollinators in Phyllanthaceae
叶下珠科花粉组织化学、花粉数和胚珠数及其与传粉者关系的研究

The nutritive reserves in angiosperm pollen grains and the pollen and ovule numbers of single flowers are considered to be correlated with the pollinating vectors. In this paper, we studied the relationships between pollen histochemistry, pollen grain number, ovule number and pollinators in Phyllanthaceae. Hymenoptera-and Diptera-pollinated species tend to have starchless, lipid-rich pollen while most Lepidopteran-pollinated species have starchy pollen grains. No correlation was found between pollinator-types and pollen number of single flowers. Flowers of fly-pollinated species have much fewer ovules than flowers of moth-pollinated species. It is suggested that the decrease in ovule number may be an adaptation to the pollinating flies, which have relatively poorer pollen-transferring ability and which transfer pollen less precisely in comparison with other pollinating insects such as moths or butterflies. Pollen grains in single flowers of shrub species were found to be almost ten times as many as that of herbs, while the tree species also have higher pollen grain numbers than congeneric shrub species. This may be due to the different flower size in plants with different life forms. Significant differences were found in the pollen ornamentation patterns under SEM between fly-pollinated and moth-pollinated species.