AND LLONAKH VALLEYS OF SIKKIM. 
153 
The Zemu area may be divided botanically into three regions — 
0, temperate forest region friom 8 — 11,000 feet, a subalpine shrub 
region from 11 — ^14,000 feet, and an alpine region from 14—17,000 
feet. On entering the valley at Zemu Samdong, 8,000 feet, the 
slopes are steep and the bottom of the valley dark and thickly 
wooded. The forest is mixed. Along with the conifers- — Fioeay 
Larixy Tsuga, Abies y JuniperuSy there occur numerous species 
belonging to the following genera: — Berherisy Ilexy EuonymuSy 
Aoety Rubu», Neilliay Rosa, Spircea, PyruSy Ribes, Pentapa- 
nax, Viburnum, Lonicera, Gaultheria, Rhododendron, Enkianthus, 
Litscea, Daphniphyllum, Elceagnus, Corylus, Betula, Alnus. 
Gradually as we ascend the Rhododendrons and Coniferce 
tend to prevail and at 10 — 11,000 feet the" forest is chiefly 
composed of them. .At 11,000 feet the character of the 
valley begins to change. The tall 'Rhododendrons disappear, 
their place being taken by intermediate forms such as R. 
Wightii and R. campanulatum, which are quite as difficult a 
.barrier. The Coniferce too begin to thin off. The valley opens 
out, becomes lighter and is more sheltered from the monsoon rains. 
The main current of the monsoon rainstorms in this region seems 
to pass up the Lachen and not to affect the Zemu and Llonakh 
much above their junction. Herbaceous species become more 
prominent, especially at the open areas near the river which have 
been cleared by the headsmen or by landslips. 
From 1] — 14,000 feet, up bo the base of the glacier, the small 
shrubs prevail- — the large trees persist only in sheltered corners, 
generally near the stream. At 12,000 feet most have disappeared. 
The floor of the upper - valley is filled with a chaos of boulders 
covered with straggling Berberis, Pyrus, Cotoneasier, Ribes, Loni- 
cera. Rhododendron, Salix, from two to ten feet high. Meconopsis, 
Cardamine, Corydalis, Lychnis, Astragalus, Potentilla, Sedum, 
Epilobium, Heracleum,, Angelica, Saussurea, Primula, Pedicularis, 
Salvia, Polygonum, Rheum, Polygonatum form the bulk of the 
herbaceous flora. From 14,000 — 18,000 feet — about the limit of 
vegetation — the prevailing genera are Anemone, Corydalis, Draha, 
Potentilla, Saxifraga, Sedum, Cortia, Nardostachys, Cremantho- 
dium, Saussurea, Leontopodium, Anaphalis, Rhododendron, Cas- 
siope, Diplarche, Diapensia^ Primula, Androsace, Gentiana, 
Swertia, Picrorhiza, Lagotis, Pedicularis, Polygonum^ Rheum, 
Salix, J uncus, Cqrex, Poa. 
The lower valley is a wet forest, the upper valley, protected by 
the giant ridge from Lama Anden to Kangchenjunga, is compara- 
tively dry. 
