How Plants Resist Hostile Forces Around Them 277 



sisting as they do of a rich store of succulent food, they cannot 

 but prove attractive to smaller animals. Thus, a good many 

 kinds, as in the Grasses, place their buds underground, whence 

 they send up their stems and leaves to the light. In buds that 

 must grow in the air, every soft protoplasmic growing point is 

 deeply buried by the leaves it is forming, for these at first lie 

 tightly against it, and only later open out to the light. Their 

 green color, moreover, must afford an appreciable measure of 

 protective coloration, which is doubtless the chief explanation 

 of the prevalent greenness of the calyx of flowers. In some 

 desert plants, where true leaves are wanting, the buds are sunken 

 deep in a hollow formed by the older tissue, and often are further 

 protected, as in the Cactuses, by a perfect cheveux de fris of 

 tough and interlocking spines. The growing points of roots are 

 well protected by their position underground, while the cambium 

 cylinder, likewise richly stored with the most nutritious of food, 

 is deeply enwrapped by the tough fibrous bark, which often 

 contains in addition a great deal of tannin, a substance strongly 

 distasteful to most gnawing animals. 



In viewing this list of adaptations, one is constantly reminded 

 of the fact that they never are perfect in operation, since animals 

 do successfully attack plants against every one of these protec- 

 tions. Like so many others of the adaptations of plants, they 

 are real and are useful, though clumsy. However, they do obvi- 

 ously afford a considerable measure of protection, enough, as it 

 seems, to permit plants to hold their own in the struggle; and in 

 a world that is full this is all that they need. 



