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Of this the Rhododendrons are the most striking example with their 
tough evergreen foliage in many instances covered with ferruginous 
wool or with glands and hairs, or with a glaucous waxy coating ; the 
fleshy corollas are another character. In the subalpine .tract they form 
in great part a forest with a general vegetation level of 20 — 30 feet, 
altitude 8 — 10,000 feet ; from 10—12,000 feet, a bush with an average 
level of 6 — 10 feet, and in the upper altitudes to 15,000 feet, a heath of 
prostrate forms which do not usually rise above 2 feet. The regularity of 
the diminution of these Rhododendrons with the altitude is noteworthy. 
Mr. George Forrest who has collected much in Western China (Yunnan), 
where the specific concentration of the genus is morem arked than even 
in the East Himalaya, has shown me photographs illustrating the general 
habit of the Rhododendrons in that region and there the smaller species 
appear to intermingle much more freely with the bush and tree types 
and frequently occur below them. either in that area, which is much 
less moist, does the genus appear to be -so antagonistic to other genera. 
The preponderance of Rhododendrons induced by the climatic factors 
is no doubt a reason for the comparative absence of variety in herbaceous 
plants. This has been suggested 'by Gamraie in the Sikkim Gazetteer, 
1894, page 102, Shrubs of other genera such as Berheris^ Pirns, Saline 
are much less prominent and rarely succeed in monopolising even a small 
area. Notwithstanding the prevalence of the Rhododendrons, they 
appear to be slow in reconquering any area from which they have been 
ejected and the shepherds seem to have little difficulty in keeping their 
pastures from being overgrown. 
Further among the conditions favouring a flora of a restricted charac- 
ter is the homogeneous geological formation. The rocks in the alpine 
area are chiefly gneissose with little of the micaceous schist which is so 
conspicuous in the Darjeeling district. I saw no indication of limestone. 
Other factors which help to explain the homogeneity are the covering 
of snow which prevails for the greater part of the year and shortens the 
vegetative season, the regularity of the moist south winds with frequent 
mists during that period, and everywhere the steep slopes which £yre 
quickly denuded and are usually but sparely covered with soil. 
Dominant Orders, Genera and Species. 
The dominant orders are Ericaceae, Primulaceae, CompositoB, Crasm^ 
laceoB, Saxifragaceae, RosaceoB ; and in a less degree, Ranunculaceae, 
Caryophyllece, JuncacoB, Cyperaceae, Graminece, ScropMarinea, Genti- 
anaceae, Salicineoe. 
The dominant genera are :---Rhododendron, Primula, Senecio, Sedum, 
Saxifraga Potentilla^ Geniiana, Pedicular is, Salix, Swertia, Meconopsie, 
