182 FLORA INDICA. 



temperate zone become common, and the flora approximates 

 in character to that of Europe, though not to the same extent 

 as that of the western Himalaya does. Shrubby Leguminosce, 

 such as Indigofera and Desmodium, Ranunculaceos {Thalictrum, 

 Anemone, Delphinium, Aconitum, etc.), Umbelliferce, Caryophyl- 

 lece, Labiatm, and Graminece, increase in numbers as we ad- 

 vance into the interior. The air becomes drier, and from the 

 increased action of the sun the temperature does not dimi- 

 nish in proportion to the elevation, the summers being warmer, 

 though the winters are colder. The forests at the same time 

 become more open, and are spread less uniformly over the 

 surface, the drier slopes being bare of trees, and covered with 

 a luxuriant herbaceous vegetation. It is only in the upper 

 part of the vaUey of the Tista, however, above the junction 

 of the Lachen with the Lachung, that this change becomes 

 marked ; and from the rapidly increasing elevation, not only 

 of the surrounding mountains, but of the floors of the val- 

 leys, it proceeds with great rapidity, and the temperate soon 

 gives place to an alpine flora. 



The subalpine zone in Sikkim scarcely begins below 13,000 

 feet, at which elevation a dense rhododendron scrub occupies 

 the slopes of the mountains, filling up the valleys so as to 

 render them impenetrable. Here the summer is short, the 

 ground not being free of snow till the middle of June. It 

 is, however, comparatively dry, and the alpine flora very much 

 resembles that of the western Himalaya and (in generic types 

 at least) the alps of Europe and western Asia ; while as we 

 advance towards the Tibetan region we have a great increase 

 of dryness, so that a Siberian flora is rapidly developed, which 

 at last entirely supersedes that of the subalpine zone, and 

 ascends above 18,000 feet. 



A small herbarium of Dorjiling plants was, we believe, 

 formed by collectors sent by Griffith while in charge of the 

 Calcutta Botanic Garden, but our knowledge of the vegeta- 

 tion of Sikkim is entirely derived from our own collections, 

 which ^^■Q. believe to be ^ ery complete. These consist of about 



