FOREST TREES OF THE PACIFIC SLOPE. 77 



mouth ; Kantishna River, one patch between head and Toklat River; Tolovana River, two 

 patches on north tributaries; Baker Creek, one patch on bead tributary; Kuskokwim 

 River, noted on its tributary Tonzona River. Also reported from upper Copper River. 



The detailed range of tamarack cast of the Pacific region will be dealt with 

 in a future bulletin. 



OCCURRENCE. 



Most abundant in sphagnum swamps and muskegs, but of largest size on better drained 

 margins of swamps and lakes, moist, porous benches, and bottomlands; thrives also on 

 well-drained hillsides. In parts of British Columbia, characteristic of damp, cool, north 

 slopes. Grows on shallow, moist soils of nearly every consistency, from stiff clay to 

 coarse sand. Thrives on moderately retentive loams, especially those with rich leaf 

 mold. Occurrence in saturated soil seems to indicate not a special requirement, 

 but ability to exist where other species more tolerant of shade can not grow. It does 

 not do well where its roots are constantly submerged. Near confluence of Tanana and 

 Yukon rivers in Alaska it occurs in open scattering stands, while in its eastern range it 

 forms rather dense, pure growths. At best, the crown cover is never very dense. Com- 

 monly associated in mixed stands with black spruce, black cottonwood, alder, and willows. 

 Other far northwestern associates have not been determined. 



Climatic Conditions. — With the widest range of all American conifers, it experiences 

 great diversity of climate. In the Atlantic region, it grows in a humid climate with 

 frequent fogs and an annual precipitation of from 30 to 50 inches; and seasonal temper- 

 ature is moderate— 30° or over 100° F. being rare. But in north British Columbia and 

 Alaska it is subjected to great seasonal ranges of temperature and to pronounced atmos- 

 pheric dryness; temperature falls to —60° or —80° F. during winter and often goes 

 above 100° F. in summer. The precipitation may be as low as 12 inches, and the growing 

 season for tender vegetables may not exceed three weeks. 



Tolerance. — Requires a great deal of light throughout life, and at no time endures 

 heavy shade. 



Reproduction. — Frequent and abundant seeder. Some seed is borne annually, but 

 especially abundant production occurs about every 2 to 4 years. Seed have only moderate 

 rate of germination and moderately persistent vitality. Young trees often produce 

 cones when from 10 to 20 years old. Conditions favorable to germination and growth 

 are fresh organic or mineral soil, with a protecting cover of spare grass .or berbs. 

 Seedlings require this slight protection at first, and then grow fairly rapidly in height, 

 so that they persist in mixture with more tolerant but slower growing species of the 

 same age. 



PICEA. SPRUCES. 



The spruces are evergreen trees with sharp-pointed, pyramidal crowns and 

 conspicuously straight, tapering trunks. The branches grow in regularly dis- 

 tant circles. Their stiff, often very keenly pointed, single leaves have a char- 

 acteristic spiral arrangement on the branches, to which those of each season's 

 growth adbere for from about seven to ten years. All but two of the North 

 American species have more or less distinctly 4-angled leaves. Of the excep- 

 tions, one species has flat and only indistinctly 4-angled leaves, while (be otber 

 species lias flat-triangular leaves. Male and female flowers are borne on the same 

 tree and on twigs of the previous year's growth. Male flowers, pollen-bearing 

 only, are drooping, yellow, bright purple, or rose-red, long or short cylindrical 

 bodies (about three-fourths inch to 1 inch by one-fourth to one-half inch), 

 while the female flowers, which produce cones and seed, are erect, yellowish- 

 green or brighl red bodies of similar form, from three-fourths inch to about 

 1^ inches in length by one-fourth to nearly three-fourths inch in diameter. 

 The cones, which are matured in one season, are cylindrical or egg-shaped, 

 always drooping or bent downward (figs. 29-33). Most spruces bear their cones 

 at the extreme top of the crown, while some bear cones only on branches of 

 the upper half of the crown. After shedding their seed, in early or late fall, 

 the cones either drop from the trees by spring or remain on the branches for 

 a number of years. The scales of spruce cones are thin and without prickles, 

 in contrast to the thick, strong cone scales of pines, which often have sharp, 

 strong prickles. The scales are firmly attached, as in the pines, to a woody 

 L5188 08 — G 



