118 



ESSENTIALS OF BOTANY 



condition is permanent. In other plants, as in Indian 

 corn, the leaf rolls up when the weather is very dry and 

 unrolls again when it receives a better supply of water. 



138. Fleshy Leaves. — 

 Many xerophytes and a 

 still larger proportion of 

 halophytes have thick, 

 fleshy leaves, sometimes 

 thick at the base and 

 tapering to a point often 

 nearly cylindrical in 

 form. The common 

 portulaea, the so-called 

 "ice-plants," and the 

 century-plant offer fa^ 

 miliar examples of fleshy 

 leaves. Leaves of this 

 form stand exposure to 

 the hottest sunshine, 

 even when the plant is 

 scantily supplied with 

 water. 



139. Leaves of Meso- 

 phytes. — The great 

 majority of foliage 

 leaves, such as tliose of 

 most common garden 

 herbs, grasses, clovers, 



and so on, belong to this class. They are neither remark- 

 ably thick nor thin, expanded nor scanty in surface, and 

 they show no such special adaptations as rolling up to 

 avoid the parching effect of excessive sunshine. 



Fig. 83. Common Pitcher-Plant 

 (Sarracenia purpurea). 



At the right one ol the pitcher-like leaves 

 is shown in cross-section. 



