2o6 tre associations of flowers 
root absorb, by their minute points, the solid, liquid, or 
gaseous substances of which the soil is composed. The 
expanded green leaves of the plant are another very im- 
portant means of nutrition, as they imbibe the ingredients 
of the atmosphere. Thus, if a plant be deprived of its 
foliage, it will perish, because the roots alone will not be 
sufficient to absorb all the nutriment requisite for it. In 
the case of the succulent plant of the rock or desert, the 
foliage performs by far the greater portion of absorption; 
the roots being generally extremely small in proportion to 
the size of the vegetable, and the soil containing little of 
that moisture which is the grand medium of the various 
substances absorbed by plants. 
The agave belongs to an order of plants which are 
chiefly exotics. 
