14 BULLETIN 680, U. S. DEPARTMENT OF AGRICULTURE. 



leaf-bearing twigs, especially the newly formed ones of the season, 

 are more or less minutely hairy. 



The small, few-scaled cones (PL IV), which nod from the tips of 

 branchlets, mature from the middle to the end of August. Their 

 scales open rapidly afterwards and usually shed the small, winged 

 seeds during September, or occasionally somewhat later. By spring 

 most of the cones have fallen from the trees. Mature cones are from 

 about three-fourths of an inch to sometimes nearly 1^ inches long, 

 and of a reddish clay-brown color. The cone scales, peculiar in being 

 sharply narrowed from about their middle, are faintly downy on their 

 outer surfaces. The seeds (PI. IV, a) are light brown. The com- 

 paratively large-winged seeds are easily borne by the wind to a con- 

 siderable distance from the parent tree. Seed-leaves, which vary, in 

 number from 3 to 4, are about one-fourth of an inch long. By the 

 third year, seedlings produce foliage like that of the adult tree (PI. 

 IV, 6). 



Western hemlock wood is narrow-ringed and of a pale yellowish 

 brown color, with a slight tinge of red. It is rather soft (" works" 

 like soft pine), and in texture is very unlike the slivery wood of its 

 eastern relative, Tsuga canadensis, which it otherwise resembles. 

 It is the heaviest of our native hemlocks, a cubic foot of dry wood 

 weighing about 32 pounds. The unfounded prejudice, still existing 

 to some extent, against western hemlock wood is exceedingly unfor- 

 tunate, because the best grades of this wood are useful for many of 

 the commercial purposes for which pine is used, while the bark of 

 western hemlock yields a much higher percentage of tannin than that 

 of the eastern hemlock ( Tsuga canadensis) , so long and extensively 

 used for tanning leather. 



OCCURRENCE AND HABITS. 



Tsuga heterophylla is a tree of the middle, moist forest zone, grow- 

 ing from sea level to 7,000 feet elevation (Map No. 4). It is more 

 abundant on the west slopes of mountains than on the east slopes, 

 being absent from the dry inland basins of Oregon, Washington, and 

 British Columbia, but reappearing on the west slope of the Rocky 

 Mountains. The largest trees occur on lower slopes, flats, stream 

 bottoms, etc., on the west slope of the Cascade Mountains and on the 

 coast ranges of Washington and British Columbia. It grows at 

 higher elevations at the south in Washington, Oregon, and California 

 than it does toward its northern limit in Alaska. Likewise, it occurs 

 at lower elevations on the coast mountains than in the Cascades and 

 on the west slope of the Rockies. With abundant atmospheric and 

 soil moisture, western hemlock thrives in poor, thin soils and on any 

 exposure, but it grows best on deep, porous, moist soils. Quality of 

 the soil and exposure become much more important with a decrease 



