4 BULLETIlSr 680, U. S. DEPARTMENT OF AGRICULTUEE. 



DISTINGUISHING CHARACTERISTICS. ;; 



The largest tamarack trees in the Rocky Mountain region are j 

 seldom over 50 feet high and 12 or 14 inches in diameter. Tamarack i 

 has a single straight, slightly tapering trunk, and a narrow, sharply j 

 conical crown of slender, horizontal branches, which, during the '[ 

 first 25 or 30 years, extend nearly down to the ground. Later the \ 

 trunks are clear of branches for one-half or two-thirds of their length. ' 

 The thin, scaly bark is reddish brown, but outwardly more or less < 

 weathered to an ashy brown. Twigs of a season's growth are smooth j 

 and whitish at first, but by winter they become a duU yellowish i 

 brown. i 



Mature leaves (the juvenile form is scattered singly on vigorous 

 leading shoots) occur in clusters of about 12 to 20 (PI. I), and are \ 

 indistinctly triangular in cross section (convex on the top side, with j 

 a ridge beneath) and from about seven-eighths of an inch to 1| i 

 inches long. In cross section the leaf shows two minute resin ducts j 

 close to its edges. j 



The cones (PI. I), matured in early autumn of one season, are pale j 

 russet-brown, as are the minute-winged seeds (PI. I,/), which escape ; 

 slowly from the gradually opened cone scales during late autumn , 

 or early winter; the upright position of the cones doubtless prevents J 

 the seeds from escaping as rapidly as do the seeds from the pendent | 

 cones of other conifers. \ 



Wood of the tamarack is a pale yellowish brown, and varies in ' 

 texture from narrow-ringed to moderately wide-ringed, according ! 

 as the trees are grown in dense or open stands. It is rather hard 

 and heavy, durable, elastic, and fairly straight-grained,^^ a cubic , 

 foot of dry wood weighing nearly 39 pounds. Large trees have a \ 

 rather thin layer of whitish sapwood, which is much thicker in young j 

 trees. The wood is used chiefly for telegraph and telephone poles ; 

 and for railroad ties, the largest trees being cut for rough lumber, i 



OCCURRENCE AND HABITS. 



Tamarack enters the Rocky Mountain region (Map No. 1) only 1 

 north of the Canadian boundary, and occurs mainly on the east j 

 side of the Canadian Rockies. It is most abundant in sphagnum j 

 swamps and muskegs; but the largest trees occur on the better- • 

 drained margins of swamps and lakes, moist, porous benches, and = 

 bottom lands. It thrives also on moist, well-drained deep-soiled 

 hillsides. In the Rocky Mountain region the tamarack grows at j 

 elevations between about 600 and 1,700 feet; its vertical distribution j 



elsewhere in its range is, however, imperfectly known at present. | 



— ___ _ < 



■ 11 01dtreesoftenhaveanouterlayer,3to4iiichesthick,spirallytwisted,witliinwMchtheearlierformed | 

 trunk wood is straight-grained. .'] 



