KASHMIR AND THE HIMALAYAS 115

at Gangotri, scarlet rhododendrons cover scores of square
miles, massed together in a dense forest reaching as far as
the eye can overlook the successive billows of the hills.
As summer comes on the petals fall, and the hillsides are
hidden under scarlet leaves, until little is left but a magnificent
 blaze of vivid colour, set against a background of
white snow and deep-blue sky. But as one ascends
gradually to higher altitudes beneath the snow-line, the
colour changes from scarlet to purple, then to lilac, and
finally, amidst the snow, the rhododendron trees diminish to
the more compact form known in England, and the colour
of the flower is often pure white.
It has frequently been observed that in the north-west
Himalayan region the southern spurs of the ranges are
barren and scarred with landslips, and, as a rule, devoid
of forest growth, whilst the northern slopes facing the
snows support a vigorous vegetation. The subsoil is the
same on either side, yet the difference in the character of
the southern and northern slopes of the mountains is so
marked as to be conspicuous even on the smallest spurs
aud eminences. This is largely due to the effects of the
sun in hot weather, and to the fact that the southern slopes
are more inhabited and cultivated than the northern.
The winter snow lies longer and is more easily retained on
the north slopes, and thus the forest trees retain the moisture
 and have a better chance of existence than is possible
on the south, where the scorched and sun-dried vegetation
 is not only subject to the effects of jungle fires, but to
destruction by herds of goats and flocks of sheep. It is
probable, also, that the hillside cultivators themselves set
fire to the grass in order to improve the quality of the
grazing.
The south-eastern Himalayas bordering Assam exhibit
in their lower valleys all the luxuriance and beauty of
tropical vegetation. Forests of bamboo cover the steep
hillsides, and in the narrow gullies and clefts of the
mountains the tree fern expands its splendid crown. The
rainfall is much more abundant and more evenly distributed
 throughout the year in these southerly districts,