104 FOREST TREES OF THE PACIFIC SLOPE. 



Tolerance. — Moderately tolerant, becoming less so with age ; endures more shade than 

 western yellow pine, sugar pine, western white pine, and lodgepole pine, but less than 

 western hemlock, western red cedar, white and alpine fir, incense cedar, Engelmann, blue, 

 and Sitka spruces. Tolerance varies with locality and region, being greatest under con- 

 ditions of best growth. Partial shade and shelter more necessary in early life where 

 conditions of growth are less favorable. At moist north it thrives in the open from 

 early youth, while in drier regions it prefers shade of weeds, brush, etc. Dense pure or 

 mixed stands of the Northwest have clean trunks for about two-thirds of the length, 

 while trees of open forests and in the Rocky Mountains are clean-trunked for only one- 

 third their length, or, in scattered stands, carry branches almost to the ground. Trunks 

 clean themselves slowly even in dense stands, which indicates tolerance of side shade ; 

 while young trees in dense stands grow rapidly in height, showing their need of overhead 

 light. 



Reproduction. — Generally a prolific seeder, producing seed every year, with specially 

 good local seed years at intervals of three or four years. Power of reproduction and 

 seed formation nearly as great as that of yellow pine throughout its range of distribution. 

 Seed with moderately high rate of germination at best, but often low, and with persistent 

 vitality. Large quantities of seed destroyed by insects and eaten by birds and squirrels. 

 Seed matured at about same time throughout range. Warm, moist, pure mineral soil, 

 or a mixture of the latter and humus, best for germination and development of seedlings; 

 reproduction rare on thick duff or vegetable matter, but abundant in humid regions after 

 layer has been burned off or broken up by logging ; unburned, logged areas are commonly 

 restocked by its northern associates, western hemlock and red cedar. In drier eastern 

 range burning over ground is usually unfavorable to reproduction, lodgepole pine, aspen, 

 and others restocking burned areas. Under most favorable conditions, reproduction is 

 extremely dense, an acre being said to carry over 30,000 trees about 3 feet high and 11 

 years old, while a stand of 26-year-old trees averaged 1,068 trees per acre, 45 feet high 

 and '61 inches in diameter. Such reproduction is frequent in Oregon and Washington. 



Bigcone Spruce. 

 Pseudotsuga macrocarpa (Torr.) Mayr. 



DISTINGUISHING CHARACTERISTICS. 



Bigcone spruce, which is a little-known tree, is distinct in appearance and 

 conspicuous among its usually lower growing associates. It has been long con- 

 sidered a variety of the Douglas fir, owing mainly to the identical, but larger, 

 form of its cones and its similar foliage. It is, however, distinct. It is generally 

 rather stunted in appearance. The wide, pyramidal crown, extending to, or 

 within a few feet of, the ground, is open and thin, owing to the fact that the 

 branches grow from the trunk at very long intervals. Those of the lower part 

 of the crown are exceedingly long, and horizontal, but somewhat drooping at 

 their extremities, while the short top branches trend upward. Characteristic 

 short side branchlets, sometimes erect, droop from all of the limbs. The trunk, 

 clear of branches for only a few feet, tapers rapidly from a thick base, reaching 

 a height of from 30 to GO or, occasionally, 75 feet, and a diameter of from 14 to 

 20 inches. The bark is early roughened at the base of young trunks. It is black- 

 ish or deep red-brown, and, in old trees, from 2 to 5 or more inches thick near 

 the bottom of the trunk. Deep, wide furrows and ridges, irregularly connected, 

 mark the bark characteristically. The thin-looking foliage is blue-green, with 

 an ashy tinge. The somewhat curved leaves (fig. 37) grow on all sides of the 

 branchlets, but by a strong twisting of their stems they appear to come out 

 mainly from two opposite sides of the twigs. They are more or less pointed, 

 but not prickly. Leaves of a season's growth remain on the branches from 4 to 

 5 years— possibly longer. The cones (fig. 37), which are very distinctive, mature 

 early in August, opening by the latter part of that month or early in September, 

 and shedding their seeds. They vary from 3J to about 6 inches in length, and 

 when open are rich dark brown. Some of the cones fall from the trees during 

 the winter, but a good many remain for a year or longer on the branches. The 



