Page:The Journal of Indian Botany.djvu/443

21 THE DISTRIBUTION OF FLORAS IN S. E. ASIA AS AFFECTED BY THE BURMA-YUNNAN RANGES.

By Capt. F. Kingdom Ward, B.A., F.R.G.S.

I propose first to give a brief account of the flora of the N. E. Frontier of Burma, secondly to indicate its relationships, and thirdly to point out the significance of the N. E. Frontier ranges as regards geographical distribution in S. E. Asia generally.

The N. E. Frontier is formed by a broad arc of very mountainous country sweeping round in a half circle from the eastern end of the Himalaya. Here it forms the watershed between the Brahmaputra and Salween drainage systems. Turning south, it forms the watershed between the Irrawaddy, rising within the curve, and the Salween. My remarks on the flora refer especially to this southern part (Lat. 26° N. Long. 98° 30' E.)

The whole region up to an altitude of 12,000 feet is covered with forest, which is divisible into (i) jungle up to 5,000 feet (ii) temperate rain forest 5,000—8,000 feet (iii) Conifer forest above 8,000 feet.

The jungle is made up entirely of Indo-Malayan forms. It contains species of Dipterocarpus, Shorea, Hiptage, Elaeocarpus, Engelhardtia, Garcinia, Caryota, Calamus and Ficus ; many lianas, such as Mus- saenda ; climbing Aroids, like Raphidophora and Pothos ; tree ferns ; and in the undergrowth many Zingiber aceae, Acanthaceae and Gesne- raceae. There are also many epiphytic ferns and orchids.

The temperate rain forest contains many big trees which rarely possess feebly developed plank buttress roots. Characteristic genera are Sehima, Gordonia, Bucklandia, Quercus, Magnolia, Acer, Rhododen- dron ; also several palm-like Araliaceac, and occasional species of Ficus. Most of the trees are loaded with epiphytic ferns, orchids and Aeschy- nanthus ; and there is a striking development of moss. There are a few lianas of temperate genera — Clematis, Hydrangea, Aristolochia. Undergrowth is not very dense except in deep gullies, it is chiefly bamboo. Small herbs abound, especially Urticaceae, Impatiens, and Strobilanthes.

In the Conifer forest there is a preponderance of Abies, bamboo and Rhododendron emuldrum. Other Conifers, such as the Chinese coffin plank tree {Juniperus sp). and a larch are curiously local ; more widely distributed is a Pseudotsuga. I must also mention here a pine,