THE VEGETABLE CLOTHING OF THE WOBLD. 



83 



myrtles, camellias, and magnolias. Acacias and 

 heaths attain here their highest development, and 

 evergreen oaks abound. The laurels occur 

 mainly near the upper limit of this zone, and are 

 found also in the next, the zone of evergreen trees, 

 which reaches the height of 9,000 feet. Next is the 

 zone of trees with deciduous foliage, which extends 

 to the height of 10,000 feet. In the tropics this is 

 only seen on elevated plains. From this to 12,500 

 feet is the zone of conifers, and thence to 15,000 feet 

 is the zone of rhododendrons. Here lofty trees dis- 

 appear, and are replaced by luxuriant meadows and 

 herbs with thick, shining leaves and magnificent flow- 

 ers, as the rhododendrons and azaleas. The last zone 

 is that of Alpine herbs, extending to the snow-line. 

 The plants are chiefly perennial, with woody roots, a 

 small amount of foliage, and brightly colored flowers. 

 Nearly all contain resinous and bitter substances. 



The Alps and other mountains of temperate climes 

 have but five or six zones. The zone of fruit trees 

 rises to about 2,000 feet. The apple and grape ascend 

 thus high, but the walnut may be found up to 3,000 

 feet. The woods here consist chiefly of beeches, 

 alders, pines, and oak. The zone of beeches may 

 reach to 5,000 feet. The birch, sycamore, hazel, wild 

 cherry, and many herbs, as the plantain, dandelion, 

 and chrysanthemum, attain their upper limit here, and 

 disappear with the beech. At the same time, we 



