Trees uf Ar/r lark ISlule 129 



SALICACEAE 



Populus troinuloidos Mic-lix. 



Trembling Aspen, American Aspen, Popple 



Habit — At luaturity usually a, siiiall t ice ilO-tiO feet in lioiglit witli a trunk 

 diameter of 1-2 feot, under optinunu conditions sometimes 100 feet tall. 

 Crown narrow, round-topped, open and irregular, consisting of slender, 

 somewhat ascending branches which often droop at the tip. Bole in large 

 trees with little taper until the crowni is reached, in smaller trees tapering 

 gradually into the crown. Propagates by root suckers. 



Leaves — Alternate, broadly ovate to orbicular, acute at the apex, rounded, 

 cordate or broadly cuneate at the base, finely serrate, 1Mj-3 inches in 

 diameter, when they lirst appear smooth, lustrous, pale green with ciliate 

 marg-bis, at maturity thin, lirm, smooth, dark green and lustrous above, 

 dull yellowish green and smooth below. 



Flowers — Appearing in late March and April before the leaves from separate 

 liower-buus, dioecious, borne in the axils of laciuiately 3-5dobed, hairy 

 scales, the whole fornung cylindrical, hairy aments, l%-l2Vlj inches long. 

 Perianth wanting. Staniens 0—12 with short, slender filaments and red- 

 dish anthers, inserted on an oblique shallow disk. Pistil solitary, enlcosed 

 at the base in the tubular, slightly oblique disk, consisting of a conical, 

 gi'een, puberulous ovary, a short style and 2 spreading, lobed stigmas. 



Fruit — A curved, pale green, thin-walled capsule, about ^/i of an inch long. 

 The capsules are borne rather loosely in naked, pedunculate aments iJ-t 

 inches long, mature Ln May and June before the leaves have attained full 

 size, and open by opposite sutures to set free the minute, light brown, 

 vvhite-comoso seeds. 



Wiixoer characters — Twigs rather slender, lentieellate, smooth and lustrous, 

 reddish brown, at length dark gray and roughened by the leaf- and lateral 

 branch-scars, i'lower- and leaf- buds distinct. Leaf -buds conical and 

 somewhat curved, slightly resinous, acute, about Vi of an inch long, cov- 

 ered by 6-7 lustrous and glabrous, reddish browTi scales scaiious on the 

 margins. Flower-buds similar but larger, more obtuse and divergent. 

 Mature bark appearing rather tardily at the base of the old trees, nearly 

 black, thick, roughened by deep fissures and broad, flat ridges. Bark 

 higher on the bole and on the larger limbs thinner, smooth, yellowisii 

 green to nearly white, roughened by areas of wart-like excrescences. 



Habitat — A "weed" tree thriving on a variety of sites, swamps excepted, but 

 preferring rather dry, upland soils. Frequent in slashes and burns, on 

 abandoned fields, limestone hills, etc. 



Kange — A widely distributed transcontinental species extending from south- 

 ern Labrador through the Hudson Bay region to Alasaka, south in the 

 United States to northern Pennsylvania, Kentucky and Missouri, and in 

 the west to Mexico and California. Zones B, C, and D. 



Uses — Wood light, soft, weaJc, close-grained, light brown with nearly white 

 sapwood. Largely used with Spruce and Fir in the manufacture of pulp. 

 Occasionally sawed into lumber and used for turnery, etc. Like the Large- 

 toothed Aspen, the tree is valuable as a cover tree, establishing itself 

 quickly in slashes and burns and protecting the soil until more valuable, 

 slower-growing species can dominate the terrain. 



