CHAPTER XXVII 

 HOW PLANTS PROTECT THEMSELVES FROM ANIMALS 



412. Destruction by Animals. — All animals are sup- 

 ported directly or indirectly by plants. In some cases the 

 animal secures its food without much damaging the plant 

 on which it feeds. Browsing on the lower branches of a 

 tree may do it little injury, and grazing animals, if not 

 numerous, may not seriously harm the pasture on which 

 they feed. Fruit-eating animals may even be of much 

 service by dispersing seeds (Sect. 453). But seed-eating 

 birds and quadrupeds, animals which, like the hog, dig up 

 fleshy roots, rootstocks, tubers or biilbs, and eat them, 

 or animals which, like the sheep, graze so closely as to 

 expose the roots of grasses or even of forest trees to be 

 parched by the sun, destroy immense numbers of plants. 

 So too with wood-boring and leaf-eating insects, and snails, 

 which consume great quantities of leaves. 



413. Some Modes of Protection from Animals. — Many 

 of the characteristics of plants may be wholly or partly 

 due to adaptations for protective purposes, while in par- 

 ticular cases we cannot be sure of the fact. Perching on 

 lofty rocks or on branches of trees, burying the perennial 

 part (bulb, rootstock, etc.) underground, growing in .dense 

 masses, like a canebrake or a thicket of blackberry bushes ; 

 all such habits of plants may be partly or altogether val- 

 uable to the plant as means of avoiding the attacks of 

 animals, but this cannot be proved. On the other hand, 



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