Alfalfa in Kansas. 



195 



structure called the keel. Within this keel are enclosed the stamens and 

 pistil. The stamens are ten in number, nine of them being joined together 

 in a membranous ring around the pistil, the tenth being free. The cen- 

 tral pistil is straight, or nearly so, in the flowers of all alfalfas, becom- 

 ing curved later as the pod grows and ripens. It is this pistil which, after 

 fertilization of the ovules within, grows into the pod, while the ovules be- 

 come the seeds. The stamens bear, at their summits, yellow sac-like 

 bodies called the anthers, which are filled at maturity with the pollen. 

 At the summit of the pistil is the surface called the stigma, to which the 

 pollen grains adhere, and on which alone they can germinate. 



For close-pollinating alfalfa flowers select a warm, sunny day. Tak- 

 ing a flower that is fully opened, i. e., in which the standard is fully 

 spread, press down upon the keel with a toothpick or other similar small 

 instrument. Instantly the keel will burst apart, and the pistil, with its 



FIG. 168. Flower of alfalfa with petals removed from one side to show the 

 organs of fertilization, c, The column of stamens that surrounds the pistil; *, a 

 stamen; a, a, anthers or pollen-sacs, which terminate the stamens. In the center, 

 among the stamens, stands the pistil, the tip of which is covered with feathery 

 hairs and is called the stigma, st. It is here that the fertilizing pollen falls. In 

 the background is one of the keel petals, k, and a wing petal, w. 



surrounding ring of stamens, will spring upward and towards the stan- 

 dard, striking it with the stigma. The pollen is jarred out of the anthers 

 by the spring-like jerk of the pistil, and flies up around the stigma in a 

 tiny cloud of fine yellowish dust, settling upon it and completing pollina- 

 tion. The pollen grains germinate, send their germ tubes down the stalk 

 of the pistil, or style, to the ovules, which they enter and fertilize the egg 

 cells therein. This constitutes the process of fertilization, and starts the 

 young embryo in its growth within the seed. Ordinarily, in the field, 

 alfalfa flowers are visited by insects which trip the flowers. This is not 

 accomplished by the honeybees very extensively, but chiefly by the small, 



