38 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. 
tions being much less vigorous. It forms pure open stands of limited 
extent (in the United States) and is also scattered among open for- 
ests of Arizona pine, western yellow pine, and occurs occasionally - 
with Apache pine. Its requirement of light is very similar to that 
of the western yellow pine. 
Chihuahua pine bears good crops of seed about every other year, 
but some cones are ripened practically every year. Reproduction is, 
however, generally sparse, which is due in part probably to the fact 
that mature cones often remain closed for several years, thus failing 
.to liberate their seeds regularly. 
LONGEVITY. 
Chihuahua pine is moderately long-lived, probably attaining an 
age of from 250 to possibly 300 or more years. Further determina- 
tions are required to establish its extreme age. Trees from 14 to 20 
inches in diameter are from 125 to 185 years old. 
LODGEPOLE PINE. 
Pinus contorta Loudon. 
COMMON NAME AND EARLY HISTORY. 
Lodgepole pine is one of the most interesting of our native species 
on account of its variable characteristics and its enormously wide | 
range (map No. 18), which extends from sea level to 11,500 feet ele- 
vation. For many years authors have endeavored to maintain that 
the form of lodgepole pine which inhabits the region from cur 
northern Pacific coast to the western Cascades is distinct from the 
lodgepole pine that grows on the high Sierras and Rocky Mountain 
plateaus. The first is known to botanists as Pinus contorta and the 
last, as Pinus murrayana and Pinus contorta murrayana. The dis- 
tinctions assembled to separate these trees are, however, one after an- 
other broken down when living trees are carefully studied throughout 
this great region. In the opinion of the writer such distinctions as 
differences in thickness of bark, size of cones and leaves, or size and 
form of the tree, may, in the case of these two forms, be consistently 
within the variations of one polymorphous species. Moreover, the 
reproductive organs of these supposedly distinct trees being essen- 
tially the same, they offer no characteristics on which to base varietal 
or specific distinction. Perhaps no other North American trees have 
given so much trouble, or left so much uncertainty in the minds of 
those who have attempted to hold them separate, as the coastal and 
high-mountain forms of this pine. Recent students of trees certainly 
have appreciated the lack of distinction between these two regional 
forms, but have been slow to depart from the time-honored judgment 
of earlier writers. It is confidently believed, however, that the lat- 
ter would have taken the broader view had they been able to study 
the trees as they grow in all their retreats. 
