STEWART: FLORA OF LADAK, WESTERN TIBET 579 
13,000 feet but there is no forest in Ladak. Trees will grow when 
they are irrigated, or in a rare spot where they can find water 
naturally, but they form a very small part of the covering of the 
country. 
Between Kashmir and Ladak there is, to be sure, a transition 
zone which is possibly widest in the Suru region, Himalayan alpine 
plants being found where there is water far into the heart of Tibet. 
Taking the flora as a whole, however, there could hardly be a more 
pronounced contrast than between these two regions. This is due 
not to altitude but entirely to water relations. The high mountains 
stop the rain-laden clouds and very little moisture gets across. 
Wherever there is enough water from melting snow, which can be 
led out by irrigation ditches to carefully prepared terraces, crops 
Fic. 1. An oasis in the Rupshu region, altitude about 15,000 feet. 
and trees flourish. Wheat or barley may be growing on one side 
of an irrigation ditch while desert plants are on the other. These 
ditches are prepared with great care and run along the hillsides 
for long distances. They are conspicuous objects because of the 
border of grass due to the extrat moisture. 
There are, as Meebold also notes, three main elements in the 
flora of Ladak, alpine, desert and oasitic. These three are very 
easily recognizable and separable. The alpine element is largely 
