Vegetation of the Himalaya. 313 



which has evidently the same cause. In the outer lofty ranges of 

 the Himalaya, the snow-lino is met with at ahout 16,000 feet, while 

 in the Tibetan part of the chain, many ridges of 20,000 feet of eleva- 

 tion are almost entirely bare of snow. 



Having thus alluded, in very brief and general terms, to the most 

 prominent physical features of the mountain chain of Himalaya, I 

 shall proceed to describe, as rapidly as is coiisistent with clearness, 

 the general character of the vegetation which is to be observed in its 

 different parts at all elevations, from the plains of India to the upper- 

 most limit of vegetable life. This would be an easy task if the vege- 

 tation were uniform throughout the whole chain, but owing to the 

 great variations of climate to which I have just adverted, there is a 

 very great difference in this respect, ^q\v, indeed, of the plants of the 

 eastern extremity of the Himalaya being identical with those which 

 occur in the far west. In general terms, it may be said, that to the 

 eastward the vegetation is very much more luxuriant and tropical, 

 and that it changes very gradually in advancing to the westward, in 

 exact proportion to the diminution in the quantity of rain. The 

 same gradual transition in the vegetable world may also be observed 

 in advancing up the valleys, or in passing across the mountains from 

 the outer valleys to those which are further removed from the Indian 

 plain ; though in the latter case, of course, the effects of gradually 

 increasing elevation must be taken into consideration as partly the 

 cause of the change as well as the decrease of humidity. 



The plains of northern India which skirt the base of the Himalaya, 

 do not (if we except the belt immediately at the base of the moun- 

 tains) present by any means a rich flora. From their situation nearly 

 on the tropics, their distance as a whole from the sea, and their proxi- 

 mity to the mountains, they are not very damp, and their climate 

 has too decided a lowering of temperature in the cold season to per- 

 mit them to be clothed with the dense forest vegetation which clothes 

 the tropical plains of South America. They are in general open 

 plains without much wood, and where not under cultivation, are 

 covered either with a dense jungle of different species of arundo and 

 saccharum, or with scattered trees of various tropical families, acaciae 

 and zizyphi being very common genera. Here and there only there 

 are patches of forest generally low and scrubby, and without much 

 underwood, or any of the fine parasitical plants and ferns which are 

 so ornamental in tropical woods. 



In the lower parts of Bengal, the proximity of the sea somewhat 

 modifies this general character ; a number of Ferns, one or two species 

 of Pothos, and a few Orchidese, among which Vaiida Roxburghii 

 and a large and fine Cymbidium are the most common, are to be 

 found. In the same way the valleys of Silhet and Assam are ex- 

 ceptional in character, but from their being inclosed with mountains 

 ol home elevation on all sides, they are scarcely to be n^garded as 



