Thistles and Nettles 323 



In the Hawthorne, the locust, and the wild orange- 

 tree some of the lower branches develop into sharp 

 spines which prick the noses of would-be assailants. 



In the bramble those hairs which clothe the stem 

 of most plants have thickened into pointed prickles. 

 In the holly the angles of the leaves have grown 

 into needle-like points, which deter animals from 

 browsing upon them, and it is noticeable that when 

 the holly develops into a tree its foliage, carried 

 up into comparative safety, becomes almost smooth. 



On the Irish gorse, a native of commons where 

 cattle wander, and of mountain-slopes where half- 

 starved sheep run wild, all the leaves are thorns. 

 The green color of these thorns shows that they 

 contain chlorophyll, and they fulfill the office of 

 the foliage, which they have entirely supplanted. 

 The whole gorse-bush, from its root to its crown 

 of honey-sweet golden flowers, is one bristling de- 

 fiance. 



The teasel (Fig. 91) is evolving its armor, which 

 is already disconcerting to a browsing vegetarian, 

 and which may become positively deterrent in times 

 to come. Its leaves are supported by strong, mid- 

 ribs, each of which bristles all down its length, with 

 saw-teeth. The side-veins are studded with smaller 

 teeth, and, while the lower sides of the leaves are 



