Belts of Vegetation.—The flora, of the Himalaya mountains, including that of the most northern parts of China, shows an almost complete identity with the genera found covering the elevated belt of the Himalaya. If we commence with the bases of these mountains, and pass successively through the several belts, and (analogous to what takes place between the parallels of latitude of 40° to 45°) experience the rapid decrease of mean tem peratures and the quick succession of vegetable productions, we first find a vegetation similar to that of the southern provinces of India. The agricultural products consist of rice, millet, amaranth, an esculent arum, ginger, turmeric, a little cotton, and sugar at the season, succeeded by wheat, barley, and buckwheat in the cold-weather months. Along with plantains, oleander, and soine of the orange tribe, we meet also with some species which were long considered peculiar to China, as Marlea begonifolia and Houttuynia cor data, with species of Chloranthus, Incarvillea, and Hiptage. On ascending, we pass through different gradations of vegetation, until, reiching the regions of the oaks and rhododendrons, which is immedi ately succeeded by that of pines, we meet another mild region, with a flora which must approximate to that of the mountains of the central provinces of China, for here we find the Chinese genera Abelia and Eurya, with Stauntonia, Kadsura, Hovenia, etc., and it is in the midst of similar vegetation that the tea-plant is everywhere found. Dr. Boyle notices the similarity of products of the Chinese tea districts and the Himalaya. He says, as the camphor, varnish, wood-oil, and tallow trees constitute a part of the natural riches of China, so we have in the Himalayas and at their foot, Camphora glandulifera, containing solid grains of camphor in its wood. .Melanorrhma usitata, Wall., yields abundance of excellent var nish ; besides Rhus vernicifera, the varnish tree of Japan, which is common in the Himalaya. Wood oil is yielded by several species of Dipterocarpus ; oil is obtained from apricot seeds, and from Prin sepia utilis in China, as it is in the Himalaya ; and paper of the Daphne cannabina is also a product common to both, as also the butter of Bassia butyracea, which abounds at Almora.
The winter months of the colder northern coun tries have a corresponding cold season in India, during which ex-tropical cereals, wheat, barley, and more rarely oats, with various kinds of pulse, are cultivated ; and many wild plants appear, very many Cyperacem, grasses, and such aquatics as Myriophyllum, Potamogeton, Vallisneria, Zan nichellia, Lenma, and others. The mountainous
regions of Afghanistan are rich in Himalayan forms,and contain an immense number of European and Persian plants, which find their eastern limits within the British Himalaya ; and many plants are found in those mountainous regions common to Europe and the Himalaya. Nepal, Bhutan, East Tibet, and the Khassya mountains present a flora which has much in common, and in a geographico botanical point of view is one of the most im portant regions in India, if not in all Asia. In the Himalaya, the genera Rhododendron, Monotropa, Pedicularis, Corydalis, Nepeta, Carex, Spirma, Primula, Cerasus, Lonicera, Viburnum, and Saussnrea attain their maximum of development. The majority of the Afghan and Tibetan plants are also on the one hand natives respectively of the Caspian steppes and N. Persia, and of Siberia on the other.
On tho Hitnalaya and on the isolated mountain ranges of the Peninsula. of India, on the heights of Ceylon, and on the volcanic cones of Java, many plants occur, either identically the same or representing each other, and at the same time representing plants of Europe not found in the intervening hot lowlands. A list of the genera collected on tho loftier of Java raises a picture of a collection man a hill in Europe. Still more striking is the faet that Southern Australian forms aro clearly represented by plants growing on the summits of the mountains of Borneo. Some of these Australian forms extend along the heights of the Peninsula of Malacca, and aro thinly scattered on the one hand over India, and on the other as far north as Japan. Along the Himalaya, at points 900 miles apart, glaciers have left the marks of their former low descent ; and in Sikkim Dr. Hooker saw maize growing in gigantic ancient morasses. Plants on the Hima laya and Neilgherries, Ceylon, and the Khassya mountains, and in the Malay Peninsula, and the moister and more equal parts of India, are identi cal with those of Java. The genus Calamus, Orchids, Araceto, Zingiberacere, and ferns are e.specially abundant ; the genus Grammatophyllum, the wonderful Nepenthacete, or pitcher plants, of which solittu7 species occur in Madagascar, Ceylon, the Seychelles, Celebes, and the 3foluccas. — Powell; Darwin, Origin of Species, 3d ed. p. 403 ; Wallace, i. p. 138 ; Hook. and Thomson, Fl. Ind.