620 PHARMACEUTICAL BOTANY 
nial herbs, included in this group, are in full leafage, and when, 
owing to the regular supply of rain during the growing season, 
the soil is plentifully supplied with water to meet the demands of 
these plants during the period of active transpiration. During 
the winter they are xerophytes. The cold of winter freezes the 
shade plant or umbrophyte, growing in sparsely shaded woodland. 
water in the soil so that the transpiration is reduced to a minimum, 
and this is associated with the fall of the leaves of the trees and 
shrubs and the death of the overground parts of the perennial 
herbs which spring up each year from their underground parts. 
The vegetation of cold temperate regions is mainly tropophytic. 
The deciduous trees and shrubs, also known as the broad- 
leaved plants and the summer-green plants, form the principal 
