314 



Science of Plant Life 



Peppermint. The square 

 stems and opposite leaves are char- 

 acteristic of the mint family. 



alfalfa, and soy beans supply large 

 quantities of rich hay for horses, 

 cattle, and sheep. The sweet peas 

 are among the most beautiful of 

 cultivated flowering plants. The 

 locust, which furnishes a very en- 

 during wood, also is a legume ; and 

 many of the valuable woods of 

 tropical forests belong to this group. 

 In the tropics and sub tropics one 

 of the divisions of this family is rep- 

 resented by the acacias, in which 

 the flowers are radial and have 

 numerous long stamens that give 

 the flower clusters the appearance 

 of balls of coarse hair. The acacias 

 are frequently cultivated as or- 

 namental trees, and they are a 

 source of commercial gums. Re- 

 lated to the acacias are the sensi- 

 tive plants (Mimosa), one of which 

 is shown on page 44. In South 

 Africa flat-topped Mimosa trees 

 are common and form one of the 

 characteristic features of the land- 



scape. 



The mint family. This family 



is marked by square stems, peculiar 



two-lipped flowers, opposite leaves. 



Climbing nightshade, ^^^ jj^ ^ spccics an aromatic 



odor. Peppermint and spearmint 



Fig. I 



one of the wild species belonging 



to the potato family. 



