SECT, xxvii.] DISTRIBUTION OF PLANTS. 303 



Teneriffe there are five successive zones, each producing a 

 distinct race of plants. The first is the region of vines, the 

 next that of laurels ; these are followed by the districts of 

 pines, of mountain broom, and of grass, the whole covering 

 the declivity of the peak through an extent of 11,200 feet 

 of perpendicular height. 



Near the equator, the oak flourishes at the height of 9200 

 feet above the level of the sea ; and on the lofty range of the 

 Himalaya the primula, the convallaria, and the veronica 

 blossom, but not the primrose, the lily of the valley, or the 

 veronica which adorn our meadows : for, although the herba- 

 rium collected by Mr. Moorcroft, on his route from Neetee 

 to Daba and Garlope in Chinese Tartary, at elevations as 

 high or even higher than Mount Blanc, abounds in Alpine 

 and European genera, the species are universally different, 

 with the single exception of the rhodiola rosea, which is 

 identical with the species that blooms in Scotland. It is not 

 in this instance alone that similarity of climate obtains without 

 identity of productions ; throughout the whole globe, a certain 

 analogy both of structure and appearance is frequently disco- 

 vered between plants under corresponding circumstances, 

 which are yet specifically different. It is even said, that a 

 distance of 25 of latitude occasions a total change, not only 

 of vegetable productions, but of organized beings. Certain 

 it is, that each separate region both of land and water, from 

 the frozen shores of the polar circles to the burning regions 

 of the torrid zone, possesses a Flora of species peculiarly its 

 own. The whole globe has been divided by botanical geo- 

 graphers into twenty-seven botanical districts, differing almost 

 entirely in their specific vegetable productions, the limits of 

 which are most decided when they are separated by a wide 

 expanse of ocean, mountain-chains, sandy deserts, salt plains, 

 or internal seas. A considerable number of plants are com- 

 mon to the northern regions of Asia, Europe, and America, 

 where the continents almost unite ; but, in approaching the 

 south, the Floras of these three great divisions of the globe 



