CLIMATE OF HIMALAYA. 253 



The vegetation of the low ranges of hills by which the Dhiins 

 are bounded externally, does not deviate much, if at all, from 

 the tropical type. They nowhere exceed an elevation of 4000 

 feet, which is not sufficient in isolated ridges to bring about a 

 sufficient change of mean temperature, to produce much altera- 

 tion in the vegetation. They are only known, I believe, to the 

 westward of Nepal, and therefore, in the drier parts of the 

 region, they are generally covered with trees the same as those 

 of the forest belt, with, in addition, a good deal of Pinus longi- 

 folia, a subtropical species of Pine, and of a dwarf species of 

 Phoenix, almost the only palm of the western Himalaya. 



From these valleys where they exist, or from the open plains 

 in other cases, the exterior ranges of the Himalaya generally 

 rise abruptly to a height of 7000 or 8000 feet, in all parts of the 

 chain, except at the point of exit of the great rivers, where of 

 course the outline of tiie mountains is much modified. I shall 

 probably better explain the structure of the mass of mountains, 

 by saying that the lateral chain which separates any two adjacent 

 river basins, generally terminates abruptly towards the plains in 

 a bold promontory 7000 or 8000 feet in height, from which 

 lateral branches parallel to the plains run in each direction, 

 gradually diminisliing in elevation till they are terminated by 

 the great rivers. After the first sudden rise, the different ridges 

 increase much more gradually, generally running nearly level 

 for a number of miles, and then rising abruptly from 1000 to 

 2000 feet. 



In ascending on the Himalaya (or indeed on any range of 

 mountains) from the base to the line of perpetual snow, the 

 change of vegetation is extremely gradual, and within a limited 

 change of altitude bai-ely perceptible, any division into groups 

 must therefore be in a great measure arbitrary. Still some 

 mode of subdivision is quite necessary for the purpose of descrip- 

 tion, as otherwise the mind would be puzzled by tlie multitude 

 of facts. The less complicated, however, the mode of division 

 is, the more intelligible it will be. It appears, therefore, quite 

 sufficient to refer the forms of vegetation to three groups, 

 similar to the three zones interposed between the equator and 

 the pole — namely, tropical, temperate, and arctic ; or, to use 

 the term more commonly applied in the case of mountains, 

 alpine vegetation. 



There is so great a diversity in the vegetation of different 

 parts of the Himalaya, that I should entirely fail were I to- 

 attempt to give any general idea of the vegetation of these 

 different zones. I shall therefore select two particular spots, 

 and by relating in some detail the gradual changes of the vegeta- 

 tion in each of these, I shall, I hope, be able to give a good 



