Adaptation to Environment. 



3 2 3 



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 Zygophyllum cornutum 

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

 gerian desert, Batis maritima 

 (Fig. i/i), growing on wet, salt, 

 tropical beaches, and Cassiope te- 



tragona (Fig. 



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 



FIG. 171. 



Batis maritima. Halophyte from a 

 tropical sea beach. After DAM- 

 MAR. 





Cassiope tetragona, 



bearing small, leath- because they are often in part, or wholly, 



After WARMING. 



Submer g ed in water the Y are in danger 



of suffering from lack of sufficient oxygen 



