FOREST TREES OF THE PACIFIC SLOPE. 49 



pine, lodgepole pines, white and red firs, sugar pine, and incense cedar ; in south, 

 elates with bigcone spruce, white fir, Incense cedar, western juniper, and Coulter, sugar, 

 limber, western white, and lodgepole pines, the last three near its upper limits. 



Climatic Conditions. — Endures wide annual ranges of temperature, but lowest and 

 highest in regions of besl growth are about zero and 100 i\ Mean annual rainfall of 

 greater part of range varies from 20 to over 60 inches, with an average <>f about 35 inches 

 where best growth occurs. Requirements of atmospheric moisture leas than for white fir 

 and sugar pine, hut greater than for Coulter pine, western yellow pine, and incense cedar. 



Tolerance. — Fairly tolerant in youth, ranking between yellow and Bugar pines and 

 permitting its seedlings and low trees to persist under shade of chaparral on east and 

 south exposures: in later life, as -tolerant of light as western yellow pine. 



Reproduction. — Proline seeder. Seed years rather irregular, but seeds locally in range 

 nearly every year. Seed of high germination (50 or 60 per cent) and persistent vitality. 

 Produces seed only at rather advanced age, becoming less productive In old age. The 

 heaviness of its seeds confines reproduction chiefly to neighborhood of seed trees. Range 

 of reproduction increased as seed trees stand on slopes, down which seed is washed or 

 blown. Birds and rodents eat large numbers of seeds and assist some in dissemination, 

 lias vigorous reproduction at higher altitudes than lias western yellow pine. Exposed 

 mineral soil is the best seed-bed. Germination not prevented by moderate shade. 



Lodgepole Pine. 



Pinus contorta Loudon. 



DISTINGUISHING CHARACTERISTICS. 



Tho pine described tinder this name is one of the most interesting of Pacific 

 species od account of its variable characters and on account of its enormously 

 wide range, which extends from sea level to nearly 11,000 feet elevation. For 

 many years a fruitless effort has been made to keep the tree which inhabits the 

 northern Pacific coast region, extending 1<> Alaska and eastward over the 

 western Cascades, and known as Pinus contorta. distinct from the tree of the 

 high Sierras -and Rocky Mountains plateaus, known as lodgepole pine (Pinil8 

 murrayana and /'. contorta murrayana). The distinctions assembled to sepa- 

 rate these trees are one after another broken down when the trees are carefully 

 studied thoughout their great range. Differences in thickness of bark, size of 

 onies and leaves, or size and form of the tree, are not to.0 great to be 

 consistently merged in one polymorphous species, as it is proposed to do here. 

 The reproductive organs of these supposedly distinct trees are essentially the 

 same. With no characters found in these organs to warrant a distinction of 

 species, the other so-called distinctions depended upon are believed to be un- 

 worthy of serious consideration. 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. Recent students of trees have been slow 

 to depart from the time-honored judgment of earlier writers. It is confidently 

 believed, however, that those writers would have taken the broader view had 

 they been aide to study the trees as they grow in all their retreats. 



In its Pacific habitat this pine is a low tree with a dense rounded or pyram- 

 idal crown, the large, much-forked branches often extending down to the ground. 

 'Phis form is the result of an open stand, which permits other pines to produce 

 a Similai form. In very close stands it develops a tall, clean, slender shaft 

 with a short, rounded, small-branched crown. This is its characteristic form 

 in its more eastern range, and has there given the name of "lodgepole pine." 

 The trunk bark of the Pacific coast form is about an inch thick over the lower 

 half or third of the stem; it is a deep purplish red-brown and has deep, rough 

 furrows and ridges which are sharply cross-cheeked ; young poles and the crown 

 branches and stems of old trees have thin, smooth, line scaly, pale brown bark, 

 with a grayish tinge. Bark of the latter character is borne mainly by trees 



