12 THE RHODODENDRONS 
Westward again, as far, indeed, as the western termination of the Himalaya, the species descend lower than in 
Bootan: an anomalous fact, for which, in our ignorance of the contrasting features which may distinguish the Eastern 
from the Central Himalaya, I can only assign conjectural causes. Among these may be the proximity of the ocean 
to the Sikkim portion of the range, and the presence of heavy mountain-masses covered with winter, and even perpetual, 
snow, to the south and east of the upper extremity of the Brahmaputra, whereas the genus is found nearly 2,000 feet 
lower than in Sikkim. The descent of the snow line in’ Upper Assam to 14,000 or 15,000 feet, is no doubt due 
to the same causes, and this is a most remarkable fact. Uniformity of temperature, excessive humidity, and a broken 
surface, produce the same effect here as in the high southern and antarctic latitudes,—favouring the formation of 
snow and its permanence, and also extending the range of tropical; forms upwards to a greater elevation, and the descent 
of temperate or arctic forms to a lower one; of which no stronger proof can be required than the descent of Rosacea 
and Hricee, and the great elevation which Raflesia, Balanophora, and other eminently tropical genera, attain on the 
Himalaya. 
Too much stress cannot be laid upon this fact, that the snow-line ascends with the latitude on the Himalaya, 
from 14,500 fect at its south-east extreme in Upper Assam, south of the Brahmaputra, lat. 27° N., to 20,000 feet at its 
north-west extreme in the regions near and beyond the Sutledge, in lat. 86° and 87° N. Had the level of perpetual 
snow remained uniform throughout these 600 miles of northing, then climate would have only annihilated the effect of 
distance from the equator. But if we allow that, ceteris paribus, a degree of latitude is the index of a change of 
300 fect in the snow-line, we must also allow that the limit of perpetual snow is 8,000 feet lower in Upper Assam than 
its height on the Sutledge Himalaya would indicate, being 15,000 instead of 23,000 feet; and, vice versd, that if 
14,500 is that limit at Assam, as determined by latitude alone, in Kunawur we should have it at 11,000 instead of 20,000. 
Only four species, 2. Dalhousie, R. Campbellia, R. argenteum, and R. arboreum grow near Darjeeling. The second 
and fourth form scattered bushes at 7,500 and 8,000 feet: the 2. argenteum is a small tree, at 8,000 aud 9,000 fect, 
strangely iated with Balanophora, Convallaria, Paris, Spheropteris, Laurus, and Magnolia. 
It was on the ascent of Tonglo, a mountain on the Nepalese frontier, that I beheld the Rhododendrons in all 
their magnificence and luxuriance. At 7,000 feet, where the woods were still dense and subtropical, mingling with Ferns, 
Pothos, Peppers, and Figs, the ground was strewed with the large lily-like flowers of R. Dalhousie, dropping from the 
epiphytal plants on the enormous Oaks overhead, and mixed with the egg-like flowers of a new Magnoliaccous tree, which 
fall before expanding and diffuse a powerful aromatic odour, more strong, but far less sweet, than that of the Riododendron. 
So conspicuous were these two. blossoms, that my rude guides called out, “Here are lilies and eggs, Sir, growing out 
of the ground!””—No bad comparison. Passing the region of Tree-Ferns, Wallnut, and Chestnut, yet still in that of the 
Alder, Birch, large-leaved Oak (whose leaves are often eighteen inches long), we enter that of the broad-spathed Arum 
(which raises a crested head like that of the Cobra de capel), the Kadswra, Stauntonia, Convallaria, and many Rosacea. 
The paths here are much steeper, carried along narrow ridges or over broken masses of rock, which are scaled by the aid 
of interwoven roots of trees. On these rocks grow Hymenophylla, a few Orchidee, Begonia, Cyrlandracee, Aroidee of 
curious forms, the anomalous genus Sfrepfolirion of Edgeworth, and various Cryptogamie, and the Rhododendron 
arboreum is first met with, its branches often loaded with pendulous mosses and lichens, especially Uswea and Borrera. 
Along the flat ridges, towards the top, the Yew appears with scattered trees of Rhododendron argenteum, succeeded 
by 2. Campbellie. At the very summit, the majority of the wood consists of this last species, amongst which 
and next in abundance occurs the 2. barbatum, with here and there, especially on the eastern slopes, 2. Falconeri. 
