196 



FLORA INDICA. 



obliquely to the axis of the chain that they have a long course 

 through a moderately dry climate. The valleys of the other 

 rivers (except the Jelam) are much more perpendicular to 

 the axis, and the humid vegetation passes almost immediately 

 into an alpine and Tibetan flora, without the intervention of 

 a dry temperate flora. 



It must not be supposed that the vegetation of the interior 

 temperate Himalaya is altogether, or even in a great measure, 

 different from that of the outer ranges. A very large propor- 

 tion of the species is the same throughout both regions, con- 

 sisting of western forms, to which even heavy rain at one sea- 

 son is not injurious so long as a great portion of the year is 

 dry, but whose progress to the east is stopped as soon as the 

 humidity becomes permanent. The rains' vegetation of the 

 outer mountains is, however, entirely absent from the inte- 

 rior, and its place is taken by such Tibetan forms as are not 

 entirely intolerant of moisture. The presence of Pinus Ge- 



Q 



m 



trifling in amount in average seasons. Pinus longifolia disap- 

 pears, with Rhododendron arboreum and its associated plants ; 

 but all the other pines continue to the upper limit of trees, or 

 to the borders of Tibet. The cultivation of the vine is only 

 carried on in this inner region, the rainy season of the outer 

 mountains preventing the ripening of grapes. 



West of the Ravi the rain-fall lias so much lessened even on 

 the outer hills, that it is only on the first range which rises 

 into the temperate zone, that the normal West Himalayan 

 vegetation (Quercusincana, etc.) occurs; while the valleys im- 

 mediately north of it, when sheltered by hills rising conti- 

 nuously to 9000 or 10,000 feet, present many of the features 

 characteristic of the interior Himalaya. The presence or ab- 

 sence of Quercus incana, Rhododendron arboreum, and Andro- 

 meda ovalifolia, on the one hand, and of Pinus Gerardiana 

 and Ephedra on the other, may be regarded as a fair criterion 

 of the two extreme climates; but there are many valleys i» 



