150 
THE VEGETATION OF THE ZEMU 
At about 13,000 feet we came to the base of the Zemu glacier. 
Here the Zemu stream divides into two, the northern branch known 
as the Poki Chu disappearing at once below the glacier and re- 
appearing some miles further up, while the southern branch or 
Chumtha skirts the base of high cliffs. We managed to get across 
the Chumtha by another snow-bridge , which even at this early 
time in the year was the only one available. We traversed most 
of the triangular area between these two streams but found only a 
very scanty flora. Continuing up the glacier we found some ‘ flats ’ 
kept cold and moist by the melting snow. Here the most con- 
spicuous plants were Primula capitataj Picrorhiza Kunrooay 
Gentiana fhyllocalyx^ prostrate Salices, Diapensia^ Diplarclie. 
Leaving the glacier we examined several of the ridges and slopes 
on the south side, ascending almost to the limit of vegetation. This 
limit, however, was reached much earlier than on the more eastern 
heights — no doubt the presence of the glaciers and the huge accu- 
mulations of snow tend to restrict vegetation to a very short period 
and to only a few hardy species. 
The 14th we spent in the valley bottom in the vicinity of the 
snow-bridge. Epilohium reticulatum Clarke was in fine flower 
from 11,000 to 13,000 feet. Its height is from 3 to 12 inches and 
its favourite habitat is the sandy crevices between the loose boulders 
by the stream. It is very handsome, with very large flowers tor 
the size of the plant. The loth opened with a steady drizzlling 
rain, but afterwards cleared. C. again ascended the main stream 
while S. followed a tributary up the hill to the north. 
The smaller rivulet-beds usually gave an easy route up the 
hills and contained a number of small species among the stones — 
species which had no chance of survival in the dense shrubby 
vegetation on the slopes. The hills on this side do not much exceed 
16,000 feet, and the amount of snow remaining in July is small 
and confined to a few hollow’s at the top. We found that most of 
these streams ran dry at about 500 to 1,000 feet above the Zemu, 
affording a strong contrast to those on the opposite side and at the 
head of the valley which are supplied by the huge Zemu glacier 
and the snowy slopes of a much higher range and with a northern 
exposure to delay the melting until the short flowering season. 
Among the rarer plants of the day^s collection was Primula 
clougata. 
Meanwhile C. had reached the Thangchung La about 17,000 
feet. Evidently the route — Kambajong to Talung — over this pass 
was beginning to lose favour as there was no sign of a used track 
up from the Zemu glacier, though a few overgrown ‘ clearings ’ and 
