DEVELOPMENT OF PLANTS 389 



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 132). The stamens soon 

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

 greatly in size during the ripening of the seed and form con- 

 spicuous brown cylinders (Fig. 280, D). As winter approaches, 

 the pedicel below the ovary and the hairs attached to it become 

 greatly elongated and the sporophyll is thus transformed into 

 a very stable parachute that is easily detached from the spike 

 and capable of floating the seed in even the lightest winds (Fig. 

 281). If this fruit chances to fall in a marsh, the torpedo-like 

 seed after a time falls from the ruptured ovary and sinks in the 

 water. When the growth of the seed is renewed, the base of 

 the cotyledon elongates, pushes off the lid at the end of the seed 

 and curves down so as to bring the root of the embryo in con- 

 tact with the mud. Hairs now develop from the lower part of 

 the cotyledon, anchoring the young plant to the ground while 

 the tip of the cotyledon remains in the seed until the food is 

 absorbed, when it is withdrawn. In the meantime, roots have 

 developed and penetrated the soil and the stem tip begins to 

 elongate, lifting up the cotyledon and making possible the for- 



