66 POLLINATION 



42. Wind Pollination.— Flowers that are pollinated by the wind 

 are ordinarily called anemophilous (wind-loving) flowers. Wind 

 pollination is in certain respects the simplest form of pollination, 

 although the flowers are often as perfectly adapted for it, struc- 

 turally, as are the flowers that depend upon animals for pollination. 

 The staminate flowers are often in catkins which hang downward 

 and yield pollen, when it is ready, to the slightest breeze. Staminate 

 catkins are especially characteristic of many trees and shrubs where 

 they are well exposed to the wind. In most of the woody plants that 

 are wind pollinated the flowers are produced early in the spring before 

 the leaves expand so that there is very little in the way of the wind. 

 In some wind-pollinated plants the pistillate flowers are also in cat- 

 kins but in many they are not and probably there is no advantage 

 in having the pistillate flowers in this type of inflorescence. 



In many wund-pollinated flowers that are not arranged in catkins 

 the stamens have such long and slender filaments that the anthers 

 hang entirely outside of the flowers and so are freely exposed to the 

 wund. Also, in the majority of wind-pollinated flowers, if we except 

 the grass and sedge families, the pollen is produced in great abun- 

 dance. It is important that this should be so because the wind is a 

 very wasteful agent. It scatters the pollen indiscriminately, far 

 and wide, and only a very small percentage of the pollen grains land 

 by chance upon the stigmas of flowers belonging to the same species 

 from which the pollen came. The pollen of anemophilous flowers 

 is in most cases light, smooth, and dry, and thus is easily blow^n 

 about by the wind. As a rule, too, they are not easily wetted; a fact 

 of importance in rainy weather since wet pollen could not be blown 

 about readily. The stigmas are usually large and w^ell exposed and 

 so are suitably fitted for catching wind-blown pollen. 



As a rule anemophilous flowers are without odor and nectar, con- 

 trasting with insect-pollinated flowers in these respects, and also, 

 in the majority of cases, in a lack of showiness. The perianth is 

 usually inconspicuous, either because of its greenish or brownish 

 color or because of its small size, and in many cases it is absent 

 entirely. When a perianth is present it usually consists of a calyx 

 only, the presence of a corolla in wind-pollinated flowers being 

 relatively rare. 



43. Cross Pollination in Anemophilous Flowers.— Although wind- 

 pollinated flowers are as a rule more simple structurally than are 

 those pollinated by animals yet they are in many cases as well fitted 



