Our ascent to the summit was by the bed of a watercourse, now a roaring torrent, from the heavy and incessant rain. A small Anagallis (like tenella), and a beautiful purple primrose, grew by its bank. The top of the mountain is another flat ridge, with depressions and broad pools. The number of additional species of plants found here was great, and all betokened a rapid approach to the alpine region of the Himalaya. In order of prevalence the trees were,—the scarlet Rhododendron arboreum and barbatum, as large bushy trees, both loaded with beautiful flowers and luxuriant foliage; R. Falconeri, in point of foliage the most superb of all the Himalayan species, with trunks thirty feet high, and branches bearing at their ends only leaves eighteen inches long: these are deep green above, and covered beneath with a rich brown down. Next in abundance to these were shrubs of Skimmia Laureola,[[59]] Symplocos, and Hydrangea; and there were still a few purple magnolias, very large Pyri, like mountain ash, and the common English yew, eighteen feet in circumference, the red bark of which is used as a dye, and for staining the foreheads of Brahmins in Nepal. An erect white-flowered rose (R. sericea, the only species occurring in Southern Sikkim) was very abundant: its numerous inodorous flowers are pendent, apparent as a protection from the rain; and it is remarkable as being the only species having four petals instead of five.
[59] This plant has been lately introduced into English gardens, from the north-west Himalaya, and is greatly admired for its aromatic, evergreen foliage, and clusters of scarlet berries. It is a curious fact, that this plant never bears scarlet berries in Sikkim, apparently owing to the want of sun; the fruit ripens, but is of a greenish-red or purplish colour.
A currant was common, always growing epiphytically on the trunks of large trees. Two or three species of Berberry, a cherry, Andromeda, Daphne, and maple, nearly complete, I think, the list of woody plants. Amongst the herbs were many of great interest, as a rhubarb, and Aconitum palmatum, which yields one of the celebrated “Bikh” poisons.[[60]] Of European genera I found Thalictrum, Anemone, Fumaria, violets, Stellaria, Hypericum, two geraniums, balsams, Epilobium, Potentilla, Paris and Convallariæ, one of the latter has verticillate leaves, and its root also called “bikh,” is considered a very virulent poison.
[60] “Bikh” is yielded by various Aconita. All the Sikkim kinds are called “gniong” by Lepchas and Bhoteeas, who do not distinguish them. The A. Napellus is abundant in the north-west Himalaya, and is perhaps as virulent a Bikh as any species.
Still, the absence or rarity at this elevation of several very large natural families,[[61]] which have numerous representatives at and much below the same level in the inner ranges, and on the outer of the Western Himalaya, indicate a certain peculiarity in Sikkim. On the other hand, certain tropical genera are more abundant in the temperate zone of the Sikkim mountains, and ascend much higher there than in the Western Himalaya: of this fact I have cited conspicuous examples in the palms, plantains, and tree-ferns. This ascent and prevalence of tropical species is due to the humidity and equability of the climate in this temperate zone, and is, perhaps, the direct consequence of these conditions. An application of the same laws accounts for the extension of similar features far beyond the tropical limit in the Southern Ocean, where various natural orders, which do not cross the 30th and 40th parallels of N. latitude, are extended to the 55th of S. latitude, and found in Tasmania, New Zealand, the so-called Antarctic Islands south of that group, and at Cape Horn itself.
[61] Ranunculaceæ, Fumariæ, Cruciferæ, Alsineæ, Geranicæ, Leguminosæ, Potentilla, Epilobium, Crassulaceæ, Saxifrageæ, Umbelliferæ, Lonicera, Valerianeæ, Dipsaceæ, various genera of Compositæ, Campanulaceæ, Lobeliaceæ, Gentianeæ, Boragineæ, Scrophularineæ, Primulaceæ, Gramineæ.
The rarity of Pines is perhaps the most curious feature in the botany of Tonglo, and on the outer ranges of Sikkim; for, between the level of 2,500 feet (the upper limit of P. longifolia) and 10,000 feet (that of the Taxus), there is no coniferous tree whatever in Southern Sikkim.
We encamped amongst Rhododendrons, on a spongy soil of black vegetable matter, so oozy, that it was difficult to keep the feet dry. The rain poured in torrents all the evening, and with the calm, and the wetness of the wood, prevented our enjoying a fire. Except a transient view into Nepal, a few miles west of us, nothing was to be seen, the whole mountain being wrapped in dense masses of vapour. Gusts of wind, not felt in the forest, whistled through the gnarled and naked tree-tops; and though the temperature was 50°, this wind produced cold to the feelings. Our poor Lepchas were miserably off, but always happy: under four posts and a bamboo-leaf thatch, with no covering but a single thin cotton garment, they crouched on the sodden turf, joking with the Hindoos of our party, who, though supplied with good clothing and shelter, were doleful companions.
I made a shed for my instruments under a tree; Mr. Barnes, ever active and ready, floored the tent with logs of wood, and I laid a “corduroy road” of the same to my little observatory.
During the night the rain did not abate; and the tent-roof leaked in such torrents, that we had to throw pieces of wax-cloth over our shoulders as we lay in bed. There was no improvement whatever in the weather on the following morning. Two of the Hindoos had crawled into the tent during the night, attacked with fever and ague.[[62]] The tent being too sodden to be carried, we had to remain where we were, and with abundance of novelty in the botany around, I found no difficulty in getting through the day. Observing the track of sheep, we sent two Lepchas to follow them, who returned at night from some miles west in Nepal, bringing two. The shepherds were Geroongs of Nepal, who were grazing their flocks on a grassy mountain top, from which the woods had been cleared, probably by fire. The mutton was a great boon to the Lepchas, but the Hindoos would not touch it, and several more sickening during the day, we had the tent most uncomfortably full.