22 THE JOUBNAL OF INDIAN BOTANY.
though it does not belong to this belt, being found on rocky grass-clad slopes between 4000 and 7000 feet ; nor does it form forests, growing with oak and alder trees in open park land.
There are also a large number of shrubs in the Conifer forest — species of Rhododendron, Euomjmus, Bibes, Bubus, Picris, Echinanthus, Bosa, Philadelphus , Deutzia, Hydrangea, Buddleia, and others ; and a few climbers, including Schizandra, Akebia, and Smilax.
In some places, between 9000 and 11000 feet, especially where it is marshy, alpine meadow is developed. Here grow species of Nomocharis, Thalictrmn, Epipactis, Allium, L ilium. Meconopsis, many Compositae, Umbelliferae, etc.
Finally, in the alpine belt are many dwarf Bhododendrons, and shrubs such as Potentilla fruticosa, species of Spiraea, Pyrus, Bcrberis, and bamboo. On the screes and rocks species of Primula, Gremanthodiuvi, Lloydia, Pedicularis, Saxifraga, Gentiana, Gassiope, Androsace-, abound; and there are a few cushion plants.
The most extensively represented order in the mountain belt is Ericaceae. Not only are there over fifty species of Bhododendron alone, but many of them grow socially, covering the summits of the mountains as heather on a Scotch moor. Other well represented genera are Impatiens, Begonia and Strobilanthes at low altitudes ; Bubus, Polygonum, Primula at intermediate altitudes ; Pedicularis, at high altitudes.
But it would give a wrong impression of the flora, did I not mention orders and genera so wealthy in species as Orchidaceae, Gcsneraceae, Leguminosac, Acanthaceae, Zingiber aceae, Banunculaceae Liliaceae, Saxifrag aceae, Bosaceae, Araliaceae, with Arisaema, Chirita, Euonymus and Aeschynanthus.
I now pass on to the question of relationship.
The North East Frontier ranges lie on the flank of the Yunnan plateau to the east, and may be regarded as forming a huge bluff over- looking the low country of Burma and Assam.
Critical examination of the flora shows a mixture of Himalayan, Indo-Malayan, Chinese and endemic forms.
The preponderance of an Indo-Malayan flora at low altitudes is easily understood, since these ranges penetrate the Indo-Malayan region to the south and west. The point to notice is that it is soon lost ; it does not extend eastwards. In the Brahmaputra valley, the Indo-Malayan flora gets as far as 30° N. in the Irrawaddy basin to about 29°, in the next valley to the east — the Salween, to about 28°, but so impoverished as to appear scarcely dominant. In the Mekong valley however it only penetrates to about the twenty-third parallel, i.e., to the tropic, and now it is sadly stricken.
