74 PRINCIPLES OF GARDENING. [CH. II 



Although an excess of water applied to the roots 

 of plants is injurious to them, yet all of them are 

 benefited by a due supply of that liquid, and the 

 supply has to be regulated by the amount of their 

 daily transpiration. The gardener knows that this 

 differs in every species, and dui'ing different seasons. 

 For instance, in a dry hot day, a sunflower three 

 feet and a half high transpired lib. 4ozs., being 

 seventeen times more than the human body ; during 

 a hot dry night, 3ozs. ; during a dewy night there 

 was no transpiration ; and during a rainy night 

 the plant absorbed 3ozs. 



Therefore the gardener finds it best to apply 

 water during dry weather, early in the morning, just 

 before the chief demand occui's, which is from sLx a.m. 

 till two in the afternoon ; and duiing moist weather 

 he refrains from the application entirely. Then, 

 again, the gardener keeps his agaves and other fleshy- 

 leaved plants in a diy stove, for they transpire but 

 sparingly in proportion to their mass, and require 

 watering but seldom, and then abundantly ; for they 

 take up, as in their native siliceous habitats, a large 

 supply, and retain it pertinaciously in defiance of the 

 long-protracted droughts to which they are exposed. 

 In the same species I have always found varieties 

 transpire abundantly, and requii'e a lai'ger supply of 

 water in proportion to the extent of their transpiring 

 surface. Thus the broad-leaved fuchsias and pelar- 



