41 G Herbarium of the Calcutta Botanic Garden. [No. 5, 



we go north, and when we reach Gnjerat has become very small 

 indeed. In Sindh there is no rain at any season. 



In the Himalaya, the rains are heaviest to the eastward, where the 

 chain is nearest the sea, and they diminish gradually, as we proceed 

 west, till they entirely disappear in the mountains of Afghanistan. 

 In the Malayan Peninsula in which both monsoons blow over sea, 

 all seasons of the year are rainy, the summer or South-West mon- 

 soon being rather drier from the intervention of the island of Suma- 

 tra, which condenses much of the rain at that season. 



In consequence of differences of elevation, three different climates 

 require to be studied in treating of the vegetation of India. These are 

 the tropical, the temperate and the alpine. Eising out of the hottest 

 part of the temperate zone into the regions of perpetual snow, the 

 slopes of the Himalaya exhibit all these forms of vegetation at dif- 

 ferent elevations, but as none of the mountains of the Peninsula 

 rise above the temperate zone, the alpine flora is found only in the 

 Himalaya. This alpine flora is found at elevations above 13,000 feet, 

 and varies with the degree of moisture. In the outer Himalaya, 

 where the snow-fall is copious and the summer humid, but with 

 bright sunshine, we have a flora closely resembling that of the Alps 

 of Europe. A similar flora is found on the highest peaks of Afgha- 

 nistan, of Persia and of Asia Minor, and beyond Europe extends into 

 the Alps of Greenland and of temperate N. America. In the more 

 arid mountains of the interior we find a purely Siberian Elora. 



In Southern India the temperate flora begins about 7,000 feet of 

 elevation, but as we advance northward, the requisite elevation gra- 

 dually diminishes till in the most northern part of the Himalaya, 

 it is not more than 4,000 feet. In Southern India therefore the 

 temperate flora is found only in isolated patches on the mountain 

 tops, but along the Himalaya it is continuous from one end of the 

 chain to the other. Here it presents three distinct types, the first of 

 which is the normal Himalayan type of forms which are adapted to 

 a climate dry at one season, wet at auother, occupying the Central 

 Himalaya. To the west, we have the European type intruding 

 upon aud mingling with it, especially in the inner ranges where the 

 climate is drier. To the east, the Japan or moist temperate flora 

 is especially developed in Khasia and Sikkiin where the climate, 



