WIND POLLINATION 307 



pollen during a Mgh, wind would be useless; indeed, 

 while we speak of wind-pollinated flowers, we must 

 dismiss tlie notion that high winds only are of value. 

 They may rather be detrimental, for the best service 

 is secured from slight air-currents and the gentlest of 

 breezes. 



In wind - pollinated plants the floral envelopes are 

 greatly reduced, so as not to be in the way of the essential 

 organs. The position of the flowers is such that either 

 they may be easily shaken by the wind, or if they 

 remain firm, their stamens are disturbed by the slightest 

 breath. The stigmas are generally large, and furnished 

 with spreading hairs, and exposed advantageously for 

 the interception of drifting pollen. But in cases where 

 stigmas are massed together they are not usually so 

 large as in other instances. In the Eeed-Mace {Typha 

 angustifolia) thousands of stigmas, which are knoblike 

 and very small, are massed together in the " mace," and 

 thus, in spite of their diminutive size, as a mass they 

 expose a large surface for the interception of pollen. 



Cross-fertilization is the rule in anemophilous plants. 

 It cannot be avoided in the numerous instances in which 

 the sexes are apart on different plants, and it is assured 

 where the sexes are both on the same plant, but in 

 different flowers. Where the flowers are hermaphrodite, 

 self-fertilization is generally avoided by anthers and 

 stigmas ripening at different times. Either the anthers 

 discharge pollen before the stigma is in condition to 

 receive it, or the stigma ripens and receives pollen from 

 another flower before the pollen can be discharged by 

 the anthers with which it is associated. In this con- 

 nection we bear in mind that a stigma is said to be 



