874 THE BATTLE IN THE MEADOW. 



employed, describes it: "The general appearance of the 

 uninanured plots is one of even growth, with no special luxuri- 

 ance of any particular plant. The herbage is very mixed, the 

 crop scanty, the color yellowish green, no one kind being specially 

 favored. Fefffftrn ovina is the predominating grass; Briza media 

 is more abundant than on most other plots. The miscellaneous 

 plants are generally very abundant, such as the buttercups, 

 Plantago lanceolata, Leontodon, lirunella vuhjaris, Achillea 

 Millefolium, Rnmex Acefosello,nndothcrB. The contrast in early 

 summer between the scanty yellowish-green herbage, profusion 

 of flowers of the various weeds, and the almost total absence of 

 flowers and rich, deep blue-green foliage of the plants in the 

 ammonia j^lot is very striking.'' 



As would be expected, almost all the plants on the experi- 

 mental plots, no matter how they were treated, were perennials ; 

 very few were annuals. Few of them were left long enough to 

 produce seeds. It would be interesting to know what would 

 have been the result had all the plants remained without cutting. 



The competition of grass for room is mainly exerted by the 

 roots and rhizomes, which form a network more or less dense 

 and varying in depth according to the plant and the soil. In 

 some cases the competition is chiefly above ground, where dense 

 tufts prevent the growth of neigliboring species. 



The changes of the seasons cause the proportion of plants to 

 fluctuate. 



As Darwin observes, in chapter 3, Origin of Species: *'The 

 struggle almost invariably will be most severe between the indi- 

 viduals of the same species, for they frequent the same districts, 

 require the same food, and are exposed to the same dangers." 



Very marked contrasts between species of the same genus also 

 occur, as Poa trivialis and Poa pratensis. This, perhaps, may 

 be partially explained by the fact that the former produces no 

 rhizomes while the latter produces many. 



