396 



PLANT PECULIARITIES 



Figure 434. — Diagram. 



Section of the epidermis of agave, "a 

 xerophytic plant. Compare this sec- 

 tion with the section of the bean leaf 

 in Figure 265. 



Plants which live in 

 desert regions, of neces- 

 sity, have to live on little 

 water. They are called 

 xerophytes (zeVo-fites :. 

 Greek, xeros, dry ; phyton,. 

 plant). Xerophytes usu~ 

 ally have long roots so- 

 that when moisture is- 

 present they may gather 

 it rapidly. Many forms 

 have little surface ex- 

 posed to the air ; the branches are few, and there are no 

 leaves. The stem, which is green in color, perforins the^ 

 work of photosynthesis. To conserve their water supply 

 further, the xerophytes have a thick epidermis and few 

 stomata. These plants 

 are an admirable illustra- 

 tion of making the most 

 of what one has. 



Desert plants live in 

 regions where it is usu- 

 ally both hot and dry, 

 but plants of the Arctic 

 Regions have many of 

 the same modifications, 

 only in a lesser degree. 

 Much of the time severe 

 cold prevents the roots 

 from absorbing water, 

 and the plant must keep 

 what it already possesses. 

 Some of the Arctic plants, Figure 435. — Bull Thistle. 



therefore, have leaves A mesophyte weed. 



