10 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 
thrive in a warm dry climate. This distribution is well illustrated 
in France, where both wild and cultivated bushes are confined to the 
northern part of the country and the cooler regions in the vicinity 
of the mountains to the east and south. They do not occur in cen- 
tral France (24), where the climate is warm and dry. The Ribes 
Fig. 2.—Limber pine (Pinus flexilis) of western North America, growing in the National 
Arboretum at Nogent sur Vernisson, Loiret, France. This tree, although thriving 
under its new surroundings, was attacked by the blister rust on two limbs, one located 
2 feet and the other 4 feet above the ground. 
of India, eight species in all, do not grow in the hot and dry areas, 
but in the Himalayan region (19) at altitudes between 7,000 and 
13,000 feet. The Ribes distribution of the North Temperate Zone 
coincides closely with that of the five-leaved pines, affording optimum 
conditions for the development of the blister rust, 
