ARMED PLANTS. 179 



This struggle reaches its climax in that belt of 

 rainless regions which girdle the earth at a short 

 distance from the tropics. The Sahara is continued 

 eastwards through Arabia, appearing again in India 

 under the name of Thur, to the south of the Punjab. 

 In the New World, Mexico forms part of this barren belt. 



The plants of these desert lands are armed 

 almost without exception ; armed to the teeth, like 

 the Bedouin who roams over the sandy waste. The 

 leaves, unable to withstand the burning sun, grow 

 tougher, and expose less surface to the light. In our 

 moist climate the herbage eaten off by browsing 

 animals is soon replaced by a more luxuriant growth ; 

 but the plants of the desert cannot hope to escape 

 destruction by a rapid renewal of the parts destroyed. 

 They defend themselves therefore by thorns and 

 spines. 



On the Riviera the number of spinous plants is 

 so great that one is at a loss to enumerate or 

 describe them. I have mentioned in other chapters 

 the cruel Acacia horrida, with its enamelled daggers 

 six inches long, the sharp weapons of the ruthless 

 Agave, the trident brandished by the Honey Locust 

 (Gleditschia), the threatening thorns of the Cactus 

 (Fig. 69), and other plants effectively if less con- 

 spicuously armed. 



Our British Hawthorn (Cratcegus oxyacantha) is 

 represented in Liguria by a species (C. monogyna] 

 which closely resembles it ; the Thistle, like its 

 patron the Scotchman, is ubiquitous ; but the golden 

 Gorse (Ulex) is absent from the Riviera. 1 * However, 

 there is a substitute, a shrub as unapproachably 



* Ulex nana, the dwarf gorse, is plentiful about Marseilles. T. H. 



12A 



