POLLINATION AND ITS INFLUENCES ON THE BEHAVIOR OF THE PISTILLATE FLOWER IN VALLISNERIA SPIRALIS

The account of pollination in Vallisneria spiralis presented here differs slightly from that given by Wylie (1917). While submergence of the pistillate flowers may further pollination in the American form, it is not of such significance in the smaller Indian form but may be indirectly helpful in bringing fresh staminate flowers into the depressions about the pistillate flowers. The present account, otherwise, supports the observations of Wylie with regard to the part played by the surface film forming the depressions to capture the staminate flowers. Since the Indian form is more like the European, the present findings indicate that the account of pollination by Kerner (1891) may be regarded as somewhat generalized. The differences in flower structure between the various forms from different regions call for a taxonomic review of the genus. The second part of the paper concerns the influences of pollination on the behavior of the pistillate flowers. The period ordinarily open to pollination is several hours, and the subsequent rate of retreat of the pistillate flower under water is very slow at first, less than a centimeter per hour. Pistillate flowers in the lake had scapes 46 cm. long; when the plants were transplanted to an aquarium with water 16 cm. in depth, the scapes attained a length of only 18 cm.