ECOLOGY OF LEAVES 



123 



So too with leaf-eating insects and snails, which consume 

 great quantities of leaves. 



143. Plants of Uneatable Texture Whenever tender 



and juicy herbage is to be had, plants of hard and stringy 

 texture are left untouched. In pastures there grow such 

 perennials as the bracken fern and the hardback of New- 

 England and the iron weed and vervains 

 of the Central States, which are so harsh 

 and woody that the hungriest browsing 

 animal is rarely, if ever, seen to molest 

 them. Still other plants, like the knot- 

 grass and cinquefoil of our dooryards, 



Fig. 



Spiny Leaves of Barberry. 



are doubly safe from their growing so close to the ground 

 as to be hard to graze and from their woody and unpala- 

 table nature. The date-palm (which can easily be raised 

 from the seed in the schoolroom or the laboratory) is an 

 excellent instance of the same uneatable quality found in 

 a tropical or subtropical plant. 



144. Plants with Weapons for Defense.^ — Multitudes of 

 plants, which might otherwise have been subject to the 



1 See Kemer and Oliver's Natural History of Plants, Vol. I, p. 430. 



