2 NUMBERS AND USES [CH. 



Although in the actual number of species the Grass 

 family is by no means the largest in the vegetable 

 kingdom, for there are far more Composites or Orchids, 

 the curious sign of success in the struggle for existence 

 comes out in grasses in that the number of individuals 

 far transcends those of any other group, and that they 

 have taken possession of all parts of the earth's surface. 

 Some species are cosmopolitan — e.g. our common Reed, 

 Arundo Phragmites; while others — e.g. several of our 

 native species of Festuca and Poa — are equally common in 

 both hemispheres. On the whole the Tropics afford most 

 species and fewest individuals, and the temperate regions 

 most individuals. 



Considering their multifarious uses as fodder and food, 

 for brewing, weaving, building and a thousand other 

 purposes, it is perhaps not too much to say that if every 

 other species of plant were displaced by grasses of all 

 kinds — as many indeed gradually are — man would still be 

 able to supply his chief needs from them. 



The profound significance of the grass-carpet of the 

 earth, however, comes out most clearly when we realise 

 the enormous amounts of energy daily stored up in the 

 countless myriads of green blades as they fix their carbon. 

 By decomposing the carbon -dioxide of the air in their 

 chlorophyll apparatus by the action of. the radiant energy 

 of the sun, they build up starches and sugars and other 

 plant-substances, which are then consumed and turned 

 into flesh by our cattle and sheep and other herbivorous 

 animals, and so furnish us with food. The whole theory 

 of agriculture turns on this pivot, and the by no means 



