574 STEWART: FLORA OF LADAK, WESTERN TIBET 
noted for its heat but the Workmans found that the sun tem- 
peratures in India rarely go to 170° F. At altitudes of 14,000- 
19,000 feet, however, they obtained maximum temperatures of 
from 183° to 204° F., although it was from 47° to 60° in the 
shade. The result is that one frequently finds it uncomfortably 
cool in the shade of a great rock while the sand is blazing hot in 
the sun. 
The plants, therefore, that are not in damp places are exposed 
to extremes of temperature. This is true even in the winter time, 
for although a little snow falls, it does not lie long in the valleys. 
The missionaries at Khalotse, however, told us that the Indus — 
remains frozen over during a part of the winter at least. 
The growing season in Ladak is a very short one, even in the 
lower parts, and a traveller who visits the country only in July 
and August can therefore find the great majority of the species. 
There are several causes for this. In the first place, there is no 
rainy season to give birth to an ephemeral desert flora such as we 
have in the American Southwest. In the second place, plants that 
are in fruit at one altitude can be found in flower at higher alti- 
tudes. Further, most of the wild flora, excluding the annual 
weeds in the villages, is perennial and the leaves can be found 
even if the flowers are missing. 
At Leh, Moorcroft reported that frosts began early in Sep- 
tember and continued until May. Barley sown May 10th was cut 
September 12th. At Spituk, nearly 1,000 feet lower, he says that 
it took barley only two months to mature. Strachey says that 
in western Tibet elevations below 14,000 feet appear to be exempt 
from night frost for the greater part of the summer quarter. At 
15,500 feet it freezes every night in the year. At 18,000-19,000 
feet it thaws only during the afternoons of July and August. While 
we were in Rupshu in August we suffered greatly at night from 
the cold. One night half an inch of ice formed and the thermom- 
eter registered 21° F, 
The country is practically without rainfall. The average at 
Leh is about three inches a year- Usually what precipitation 
there is falls at night and only on the mountain ridges and passes- 
A number of times in July and August we noticed that a light 
blanket of snow fell on the mountain tops while there was 0 
