DEVELOPMENT OF PLANTS 371 



flowers of the spike bear a single pistil each (Fig. 280, C), which 

 consists of a large flat stigma, style and ovary containing a single 

 ovule and supported upon a hairy stalk or pedicel. The micro- 

 spores are carried to the stigmas of the pistils by the wind. 



Such anemophilous flowers are characterized by several fea- 

 tures well illustrated in the cat-tail. The microspores must be 

 produced in large numbers since the chance of one reaching the 

 stigma of another plant rapidly decreases as the distance tra- 

 versed by the spores increases. This probably accounts for the 

 growth of many anemophilous plants in dense colonies since 

 the close proximity of the plants greatly increases the chance 

 of the microspores reaching the stigmas. The Pinales, grasses, 

 willows, oaks, etc., are other illustrations of a very large series 

 of plants, some 10,000 in number, that have a similar habit. 

 Anemophilous flowers are inconspicuous and simple in structure. 

 You will notice that showy perianths, nectar and perfume glands 

 are only developed in such flowers as utilize insects for the distri- 

 bution of the microspores. The stigmas of anemophilous flowers 

 are usually large and hairy or brush-like and conspicuously ex- 

 posed so as to increase the chances of catching the microspores, 

 thus reducing the dangers of this rather risky method of cross- 

 ing. You will also observe that anemophilous flowers are usually 

 characterized by having imperfect flowers, the stamens and pis- 

 tils being developed on different parts of the plant, or on dif- 

 ferent plants. By this arrangement, the advantages of crossing 

 are secured and it also happens that the microspores are either 

 scattered before the stigmas of neighboring flowers are mature, 

 or, more frequently after they have withered and are therefore 

 no longer capable of catching and nourishing the spores. In 

 this way it comes about that the microspores, even when close 

 to the pistillate flowers as in Typha, are often only of service 

 when carried to some earlier flowering plant whose stigmas are 

 mature. In the cat-tail, the microspores are shed a day or so 

 before the stigmas on the same spike are mature and so there 

 must result the benefit that comes from crossing two more or 

 less widely separated plants (page 128). The stamens soon 

 perish after the discharge of their spores, but the pistils increase 



