38 BULLETIN 460, IT. 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 } 7 ears. 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 EABLY HISTOBY. 



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. 13), 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 our 

 northern Pacific coast to the western Cascades is distinct from the 

 lodgepole pine that grows on the high Sierras and Eocky Mountain 

 plateaus. The first is known to botanists as Pinus contorta and the 

 last, as Pinus rrwrrayana 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. 



