FOREST TREES OF THE PACIFIC SLOPE. 153 



Endures most shade with favorable moisture, soil, and climatic conditions. Growth and 

 size is checked ordinarily in proportion to intensity of shade endured. 



REPRODUCTION. — Prolific seeder under favorable conditions, every 2 to 3 years or more; 

 some seed borne locally every year. Bulk of seed from thrifty, mature trees in full sun- 

 light. In exposed places, even small scrubby trees bear seed. Seed has fairly high rate 

 of germination, and persistent vitality. Moist vegetable mold best seed-bed, but germi- 

 nation and growth of seedlings good on moist mineral soil. Partial shade favorable to 

 early seedling stages. Reproduction good under old trees and in open, but especially 

 good in openings and under 'binned stands, where the dense thickets frequently exclude 

 other more valuable trees. In cool, moist places, however, white fir often enters such 

 thickets and predominates. Frequently the first of conifers in chaparral and oak growth' 

 at lower edge of timber belt, proving its great adaptation to different degrees of light, 

 moisture, and soil, and its general hardihood in seedling stages. 



THUJA. ARBORVITJES. 



The arborvittps are commonly known as cedars. They .arc medium to very 

 large sized evergreen trees. The foliage consists of minute, overlapping, scale- 

 like leaves, arranged as in Libocedrus, and conspicuously flat, on short side 

 branchlets, and the branchlets are arranged in one plane, forming a flat spray. 

 Seedling leaves are narrowly lance-shaped and sharp-pointed, and spread widely 

 from the stem. The very light wood has an exceedingly characteristic aromatic 

 odor. Male and female (lowers are borne on the same tree, usually on different 

 twigs. They are minute and inconspicuous, especially the female flowers. As 

 a rule, they open in early spring. The small solitary cones (figs. 59 and 60) 

 mature in one season, shedding their minute, very narrowly winged seeds in 

 early autumn. The cones, strongly bent hack upon the branchlets, are light 

 russet-brown, and composed of about 8 thin scales, arranged in pairs, each pair 

 alternating at right angles with the preceding one. as in the arrangement of 

 the leaves. The two or three middle pairs, which are larger than the others, 

 bear 1! seeds under each scale. The thin, gauzy seed-wings (on two sides of the 

 seed, and always lighter colored than (be body of the seeds) are very buoyant, 

 so that they may be carried by the wind for a considerable distance from the 

 parent trees. Minute resin-cells in the seed-coats give the seed a strong aro- 

 matic odor. 



Wood exceedingly valuable for timber. Particularly famed for its durability 

 under all kinds of exposure, and especially useful in ground and water construc- 

 tion where great strength is not required. 



Two species are indigenous to the United States and Canada. One. a small 

 or medium-sized tree, inhabits the northeastern States and adjacent Canadian 

 Provinces, while the other, a very large tree, grows in the northwestern States, 

 where it extends far northward in the coast region. 



Western Red Cedar; Red Cedar. 



Thuja plicata Don. 



DISTINGUISHING CHARACTERISTICS. 



The lumbermen's and woodsmen's name for this tree is " red cedar," or 

 simply "cedar." The former name, while fairly applicable to the dull, slightly 

 reddish brown wood, is unfortunate in view of the fact that two or three 

 widely known eastern junipers with really red wood are most persistently called 

 "red cedar." and probably always will be, for they were known nearly a cen- 

 tury before this western cedar was discovered. 



The most prominent characteristic of western red cedar is its decidedly 

 conical trunk form. Very old trees are enormously "swell-hutted" and are con- 

 spicuously in-folded or fluted at the base and for from 10 to 20 feet above it. 



