FOREST TREES OF THE PACIFIC SLOPE. 91 



for good germination. Natural reproduction usually abundant under mature spruce on 

 damp moss over considerable organic soil. Reproduces poorly on thick leaf litter under 

 broadleaf trees. Moss-covered decayed logs favor germination, as does moist mineral 

 soil near streams. Tolerance of seedlings permits them to thrive under a crown cover 

 which shades out most associates. 



TSUGA. HEMLOCKS. 



The hemlocks are evergreen trees with soft, flat or rounder! triangular leaves. 

 Their branches grow at irregular intervals from each other. The slender ter- 

 minal sprays droop gracefully, and the slender leaders droop or nod conspic- 

 uously from the tops of the crowns. They are large trees with broad pyramidal 

 crowns and long, only slightly tapering trunks, with the characteristically 

 rough, hard hark narrowly ridged and furrowed. The bark contains tannin, 

 which gives it an astringent taste, and when broken it displays a clear choco- 

 late-red color. The leaves, which have small, thread-like stems, are spirally 

 arranged around the branch, but by the twisting of their stems they appear 

 to grow mainly from the two opposite and the upper sides of the branches; 

 thus forming, in one western species, very Hat sprays. The leaves of hemlocks 

 are peculiar in having a single resin-duct, which is seen in a cross-section in 

 the center near the lower surface. Leaves of a season's growth remain on the 

 trees for about ;! to 6 years. Male and female flowers are borne separately 

 on different parts of the same tree on sprays formed the preceding season. 

 The female flowers grow at the ends of the sprays, while the male flowers are 

 borne singly from buds at the bases of the leaves near the ends of the branch- 

 lets. Female flowers, producing cones and seed, are small, greenish, scaly 

 bodies, while the male flowers, pollen-bearing only, are small yellowish bodies 

 attached by thread-like stems. The cones of the hemlocks mature in one 

 season, and are composed of thin overlapping scales, beneath each of which 

 L' winged seeds are borne; only the scales in about the central half of the 

 cones, however, hear fertile seeds, those above and below this part being 

 imperfect. The small seeds are easily wafted by the wind and thus may be 

 widely disseminated. Seed-leaves of our species, 3 to 4, and very short. 



Hemlocks are important forest trees both for saw timber and tanbark. As 

 yet thejrwood is of comparatively lower commercial value than that of the pines, 

 firs, and spruces, often associated with hemlock. Unquestionably, however, the 

 commercial importance of hemlock wood will be greatly increased as the supply 

 of other timbers, abundant now. is reduced. The true value of western hemlock 

 timber has not been appreciated on account of its name, since it has been con- 

 fused with the eastern hemlock, which produces wood of inferior quality. 



Four species of hemlock are indigenous to the United States and portions of 

 Canada. Two of these inhahit the eastern United States and the adjacent 

 Canadian provinces, while two are found in the Pacific forests. 



Western Hemlock. 



Tsuya heterophylla (Raf. ) Sargent. 



DISTINGUISHING CHARACTERISTICS. 



Western hemlock is a large forest tree. Its tall, clean, smooth-looking trunks, 

 fine foliage, and drooping branchlets distinguish it readily from associates. The 

 trunks taper very gradually. Forest grown trees have small narrowly pyram- 

 idal crowns of slender branches, and are from 1275 to 100 feet high and from 

 - to 5 feet in diameter. Occasionally, much larger trees are found. The hark 

 of larger branches and young trees is thin, finely scaly, and russet-brown, while 



