WESTERN YELLOW PINE IN OREGON. 5 
dense. The needles are usually from 4 to 6 inches long, on the best 
soils as long as 1 1 inches ; and they are borne in clusters of three. 
The term "bull pine" is frequently applied to the younger yellow 
pines in an uneven-aged stand, usually those of rapid growth up to 18 
or 20 inches in diameter and 100 or 150 years old. These immature, 
rapid-growing trees, or "bull pines," are quite different in appearance 
from the mature trees, or " yellow pines"; the bark of the young 
tree is much thicker, darker colored, and more furrowed; the crown 
s denser, longer, and more pointed; the wood is heavier, more sappy, 
and coarser grained ; and the annual rings are more clearly defined. 
This has sometimes led to the belief that "bull pine" is a distinct 
species of pine, which it is not. Sometimes, particularly on wet soils, 
a tree will retain the "bull pine" characteristics to a considerable age 
and until it is 30 or more inches in diameter. The term "bull pine" 
is synonymous with the term "black jack," which is used in Arizona 
and New Mexico to denote young yellow pines; the relation between 
"bulT ? and "yellow" pine is analogous to that between "red fir" and 
"yellow fir" (the two types of the coast Douglas fir), or between 
"sapling pine" and "cork pine" (the two types of the Lake States 
white pine) 
REQUIREMENTS. 
CLIMATE. 
Western yellow pine flourishes best in the heat and dryness of a 
continental climate, such as that on the interior plateaus and moun- 
tain slopes. In the north or on the highest slopes, where the growing 
season is cold, its development is much poorer than where the sum- 
mers are long and warm. Though it shows a preference for sunny 
climates and warm situations, it can, however, endure severe winters 
and temperatures far below zero. In situations where it flourishes 
in central and eastern Oregon, the mean annual temperature goes as 
low as 42° F. and the mean summer temperature ranges from about 
50° to 60° F., a maximum temperature of 100° F. being not 
uncommon. 
Yellow pine will resist drought better than any other important 
commercial tree in the State. It forms splendid forests where the 
precipitation is only 18 inches a year and the summer dry season is long. 
Where the rainfall is but a little less than this the forest gives way 
to a treeless, sagebrush, or bunch-grass flora. Yellow pine also does 
well where the precipitation is much heavier — 40 inches or more — 
but its development is by no means proportionately better in the 
wetter climates. It flourishes also in the mild, humid, insular cli- 
mate of the Willamette Valley, which is almost the antithesis of that 
of the eastern Oregon yellow-pine ranges. 
