LICHENS. 11 



mountain, appeared at intervals a few stunted birches, dwarf 

 willows, and juniper-trees ; mosses and lichens came next ; 

 and lastly, rugged and frowning rocks, among which occa- 

 sionally, and wherever the surface of the rock became visi- 

 ble, a few lichens, though often incrusted with snow, peeped 

 forth, as if wishful to assert the empire of Mora, even on 

 the verge of perpetual winter. 



Who that ever visited the island of Teneriffe does not 

 remember with delight the five zones of plants, which the 

 Peak exhibits ? Zones, beautifully arranged in stages one 

 above the other, and rising to the height of one thousand 

 seven hundred and fifty toises. 



The first zone, that of the vines, sweeps upward from the 

 sea- shore to an elevation of five or six hundred yards. It is 

 well cultivated, and varied with farm-houses and cottages, 

 among which grow giant spurges, mesembryanthemums, and 

 flowering shrubs, of which a considerable number exhibit, in 

 their succulent leaves and tints of bluish green, characteristics 

 which distinguish the vegetation of Africa, Noble groups 



