PLANT LIFE. 



45 



a disk at whose edges are the stamens, petals and se- 

 pals. This widened disk-like portion may turn up and 

 surround the pistil so that the other organs are borne 

 above the ovary instead of below it. The flower in- 

 stead of being symmetrical may be one sided. The 

 members of each part are also subject to modification 

 and any of the parts may be lacking, although of 

 course stamens and pistils are not both absent in the 

 same flower. 



Fertilization. Many flowers secrete nectar, a sug- 

 ary liquid, which is eagerly sought by insects. Many 

 of the modifications sug- 

 gested above are to at- 

 tract insects (or humming 

 birds) to the flowers and 

 to cause them to come in 

 contact with the stamens 

 and pistils in their at- 

 tempts to obtain the nec- 

 tar. In this way pollen 

 is carried from one flower 

 to another and fertiliza- 

 tion is made more certain. 

 As a general rule, which 

 has, however, many ex- 

 ceptions, we can safely 

 say that showy flowers, 



* ., J a, stamens; b, proboscis of bee; c, where 



aS Well aS inCOnSplCUOUS bee receives pollen. 



ones, which produce an 



abundance of perfume or honey, are usually pollinated 

 by the aid of insects or birds, while those that are not 

 so, are wind pollinated, i. e., the pollen is fine and pro- 

 duced in great abundance and floats in the air, some 

 of it eventually, by chance, falling on the stigma of 

 flowers of the same kind. Most grasses (e. g., corn), 

 many of the trees such as oaks, willows, pines, etc., 

 are wind pollinated. 



Close Fertilization. In a number of cases the pol- 

 len is set free from the stamen before the flower opens 



BUMBLE-BEE POLLINATING RED 

 CLOVER. 



