. CALCUTTA BOTANIC GARDEN. 39 



mass of land to the north, the summer winds blow strongly from the 



i 



south, while the winter winds are northerly. The south wind, com- 

 monly called the south-west monsoon, is always a sea wind, and there- 

 fore brings rain. The summer is therefore the rainy season in India. 

 The northern winter wind is generally a land wind, so that the winters 

 are generally dry. To this there are two exceptions, the coast of the 

 Carnatic and the Malayan Peninsula, in both of which the north-east 

 monsoon is a sea-breeze, and therefore a rain-bringing wind. 



The normal climate of India is divided into a cold, hot, and rainy 

 season, but the amount of rain depends on the position of each place. 

 The west coast of the peninsula, which presents to the south-west wind 

 a lofty range of mountains, is extremely rainy at one season, but the 

 east coast, being'sheltered by the higher hills to the westward, is much 

 less so. On the Ghats the rain-fall diminishes as we go north, and 

 when we reach Gujerat 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 sea- 

 sons of the year are rainy, the summer or south-west monsoon being 

 rather drier from the intervention of the island of Sumatra, which con- 

 denses 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. Rising 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 different 

 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 

 Blow is found on the highest peaks of Afghanistan, of Persia, and of 

 Asia Minor, and beyond Europe extends into the alps of Greenland 

 and of temperate North America. In the more arid mountains of the 

 interior we find a purely Siberian Flora. 



