. Elementary biology; an introduction to the science of life . Fig. 138. Pollenation by water The tape-grass {VaHisneria) is a dioecious water plant. The pistillate individual grows up to the surface of the water, where the flowers, a, are opened, while the staminate indi- vidual remains beneath the surface. The staminate flowers, b, are detached from the stalks and rise to the surface, where they float about and gather in large numbers in the quiet stretches of water close to solid objects of various kinds. When one of these float- ing stamen flowers comes close to the pistillate flower of th
. Elementary biology; an introduction to the science of life . Fig. 138. Pollenation by water The tape-grass {VaHisneria) is a dioecious water plant. The pistillate individual grows up to the surface of the water, where the flowers, a, are opened, while the staminate indi- vidual remains beneath the surface. The staminate flowers, b, are detached from the stalks and rise to the surface, where they float about and gather in large numbers in the quiet stretches of water close to solid objects of various kinds. When one of these float- ing stamen flowers comes close to the pistillate flower of the species, the anther is brought into direct contact with the stigma, and thus pollenation is effected 2. 7^i7)ic relations. The stamens and stigmas of some species of plants do not ripen at the same time, close pollenation being thus impossible in these species. The pollen ripens before the stigma in maize, in the mallows, in many species of the aster family, in the creeping crowfoot, and in the sage. The stigmas ripen ahead of the stamens in the common plantain, in the potentilla, or cinquefoil, and in the oriental grass known as Job's tears.
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