2o6 THE STORY OF THE PLANTS. 



now dominant or leading orders, while others are 

 hardly more than mere belated stragglers or loi- 

 tering representatives of types once common, but 

 now outstripped in the race by younger competi- 

 tors. I cannot close without briefly describing to 

 you the main divisions of such orders or groups, 

 as now accepted by modern botanists. 



The widest distinction of all between plants 

 is that which marks off the simpler and earlier 

 forms, which are wholly composed of cells, from 

 the higher and stem-forming types, which are 

 also provided with systems of vessels and woody 

 tissue. The first class is known as Cellular 

 Plants; the second class as Vascular Plants. 

 These are the greatest and most general divisions. 



The Cellular Plants comprise many sorts, 

 from the simple one-celled types which float freely 

 in water, up to the relatively high and complex 

 seaweeds, which produce large fleshy fronds, and 

 often display a considerable division of labour 

 between their various parts and organs. Still, as 

 most of them live in water, either fresh or salt, 

 and wave freely about in the liquid that surrounds 

 them, they have no need of an elaborate system 

 of conducting vessels, because every part can 

 drink in water and dissolved food-salts from the 

 neighbouring pond, sea, or river. Still less have 

 they any necessity for a woody stem, which would 

 only be a disadvantage to them in stormy weather. 

 Hence most of the cellular plants (with certain ex- 

 ceptions to be noted hereafter) are water-weeds; 

 while most of the vascular plants (with other ex- 

 ceptions to be similarly treated) are land plants. 

 In particular trees and shrubs, the highest forms 

 of plant life, are invariably terrestrial. 



Various successive stages of these cellular 



