Thistles and Nettles 325 



thus effectually protected, their upper sides are not 

 always left unguarded. About one teasel in three 

 has its upper leaf-surfaces dotted over with prickles, 

 not very sharp to the fingers, but probably well 

 able to hurt the lips and tongue of a browsing 

 animal, and these prickles, by the bye, are interest- 

 ing to the botanist, because they grow out of the 

 leaf-surface, and not, after the usual habit of prick- 

 les, from the veins. A hungry rabbit, feeding 

 among the teasels, would be likely to satisfy his 

 appetite with those leaves having their upper sur- 

 faces soft and smooth, and to spare the more 

 bristly individuals. So these well-guarded plants 

 survive to set their seed, and become progenitors 

 of young plants, which will inherit the parental 

 habit of bearing leaves with prickles on both sur- 

 faces. 



The botanist draws a distinction between a prickle 

 and a thorn. A prickle can be removed with ease 

 from the stem or leaf on which it grows. It is 

 not incorporated with the wood, but merely, and 

 often very lightly, attached to the bark or to the 

 surface or edge of the leaf. 



A thorn is, on the contrary, a fixture. The 

 woody fibre of the plant runs up into it, and it 

 cannot be detached without considerable difficulty. 



