344 PLANT-LIFE 



stimulans of Java may liave as disastrous consequences 

 as snake-bites. Horses have been known to have been 

 killed by the stings of the Australian tree Laportea 

 mormdes. 



Other points in the protective equipment of plants 

 by which browsing animals are induced to maintain a 

 respectful distance are thorns, spines, and prickles. 



Thorns are really shoots which, through lack of nutri- 

 tion, have failed to develop, and hence have become 

 woody and pointed. In the Hawthorn {Gratwgus 

 Oxyacantha) the tender young leaves are protected by 

 thorns, and similar protection is afforded by the thorns 

 of the Blackthorn, or Sloe {Prunus spinosa). 



A spine, strictly speaking, is a leaf, or part of a leaf, 

 modified on account of disturbances in nutrition. The 

 spines of the leaf of the Holly (Ilex) are the sharply 

 pointed ends of leaf -veins. The Gorse, or Furze, is most 

 efiectively protected by a complete armoury of branches 

 which have been modified into thorns, and leaves that 

 are aborted into spines. 



Prickles are outgrowths of the epidermis and the 

 tissue immediately beneath it'; they may be regarded 

 as hairs, many -celled, and of larger growth. They are 

 usually quite easily detached without tearing or seriously 

 impairing the epidermis. The principal use of the 

 prickles of Roses and Brambles is in climbing, but they 

 also serve to ward ofE animals. The Scotch or Burnet 

 Rose (Rosa spinosissima, Plate LXX.), which does not 

 often grow more than a foot high, and occupies dry, 

 bushy places, heaths, and sandy sea-coasts, simply 

 bristles with prickles of varying length. These prickles 

 are not suited for climbing, nor does the plant attempt 



