Adaptation to Environment. 



323 



208. Character of Halophytes. 



— The halophytes have essen- 

 tially the same character as the 

 xerophytes ; for although they 

 grow in soils abundantly sup- 

 plied with water, their roots ab- 

 sorb it with great difficulty. 



Whatever be the cause of the 

 difficulty to plants in obtaining 

 water, the methods of adaptation 

 to the unfavorable conditions for 

 absorbing water are essentially 

 the same, as will be seen by com- 

 paring Zygophylliim cornutum 

 (Fig. 170), a plant from the Al- 

 gerian desert, Batis maritima 

 (Fig. 171), growing on wet, salt, 

 tropical beaches, and Cassiope te- 

 tragona (Fig. 



Fig. 171. 



Batis maritima. Halophyte from a 

 tropical sea beach. After Dam- 

 mar. 



Fig. 172. 



Cassiope tetragona, 

 bearing small, leath- 

 ery, in- rolled leaves ; 

 from Greenland. 

 After Warming. 



172), growing 



in the cold soil 



of Greenland. 



In each of 



these plants 



the reduction of the transpiring surface 



is very marked. 



209. Character of Hydrophytes. — ^The 

 hydrophytes are abundantly supplied with 

 water and do not need to provide special 

 devices to guard against its loss. But 

 because they are often in part, or wholly, 

 submerged in water they are in danger 

 of suffering from lack of sufficient oxygen 



