172 FLORA INDICA. 



further 



face by mountains rising everywhere to the level of perpetual 

 snow, are absolutely without rain during the monsoon. In 

 Sikkim and Bhotan, where the wide valleys are perpendicu- 

 lar to the axis of the chain, and correspond to the direction 



are heaw till we nenetrate far 



irreat 



occur even m 



adjacent valleys; thus the transverse chain of the npper Tista 

 makes the climate of the higher parts of the Lachen valley 

 much drier than that of the Lachung river, though the two 

 arc only a few miles apart. 



We meet, therefore, in the Himalaya, with all the modifi- 

 cations of climate which have already been enumerated as oc- 

 curring in India, and the aspect of the mountains varies with 

 the climate. In the permanently humid parts the mountains 

 are covered everywhere with an uniform sombre forest, mask- 



dull 



scenery. This 



limit of trees, at 12-13,000 feet, and is succeeded by grassy 



which ascend to the snow-line. Forests are also 



ures 



plentiful where the dry season is well marked and the rains 

 abundant; but they are there confined to the shady and 

 moister exposures, while the sunny slopes and all the lower 

 hills are grassy and rocky. The permanently arid mountains 

 of the extreme west are barren and rocky, and devoid of trees 

 at all elevations. 



In the temperate valleys of the inner Himalaya, where the 

 rain-fall is moderate in amount and the ground is perma- 

 nently covered with snow during winter, and where the hot 

 summer's sun powerfully stimulates vegetation, the mountain 

 slopes present a delightful intermixture of beautiful forest and 

 of luxuriant vegetation ; while above the limit of trees the 

 compact turf is enamelled with myriads of lovely flowers, nou- 

 rished by the melting snows and the genial warmth of summer. 

 To this, however, as we penetrate further into the interior, a 

 barren, treeless climate rapidly succeeds, in which the princi- 



