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TEXTBOOK OF BOTANY 



and flat and look exactly 

 like leaves; one can tell 

 that they are branches only 

 by noticing that each one 

 grows from the axil of a 

 scale-like leaf. 



The thick green stems of 

 the members of the cactus 

 family and of some other 

 plants living in very dry 

 regions take on remarkable 

 shapes. The leaves and 

 most of the branches of 

 nearly all cactuses are re- 

 duced to scales or spines. 



The advantage of such an 

 FIG. 126. A cactus (Opuntia), . 



whose stem is thick and green, and arrangement will appear m 

 whose leaves are merely spines. Connection with our Study 



of leaves. The stems of 



cactuses not only manufacture and store food; they are 

 organs for water storage as well, and are often an important 

 source of water for travelers in the desert where these plants 

 grow. The stem of 

 the "nail-keg cactus " 

 is said to yield some- 

 times as much as a 

 pint of water. 



223. Runners. 

 This name is given 

 to certain branches 

 (of the strawberry, 

 for example), which 



sprawl on the surface 



^ , FIG. 127. The strawberry geranium 



Of the ground, have (Saxifraga-sarmentosa), which bears runners 



long internodes, and much like those of a strawberry. 



