XEKOPHYTE SOCIETIES 
191 
FIG. 169. The spring - W \- v 
beauty (Claytonia), | 
showing subterranean 
tuber-like stem sending leaf and flower-bearing 
stem above the surface. After ATKINSON. 
turn of the moist season 
these underground parts 
develop new exposed 
surfaces. In such cases 
it may be said that at 
the coming of the drouth 
the plant seeks a sub- 
terranean retreat. 
A little less decrease 
of exposed surface is 
shown by the deciduous 
habit. It is known that 
certain trees and shrubs, 
whose bodies remain 
exposed to the drouth, 
shed their leaves and 
thus very greatly reduce 
the amount of exposure ; 
with the return of mois- 
ture, new leaves are put 
forth. It will be re- 
marked, in this connec- 
tion, that the same 
habits serve just as well 
to bridge over a period 
of cold as a period of 
drouth, and perhaps 
they are more familiar 
in connection with the 
cold period than in con- 
nection with the drouth 
period. 
136. Temporary reduc- 
tion of surface. While 
the habits above have to 
do with regular drouth 
