187 



POPLAES. 



82.— QuAKiNa Aspen or Asp. American Aspen. {Populus 

 tremuloideSj Michaux.) 



One of the most widely distributed of our forest trees, but of little 

 value as a timber tree, yet of considerable importance for quickly cov- 

 ering mountain and hillsides denuded by fires, thus furnishing the neces- 

 sary conditions for the growth of other longer-lived and better timber. 

 Twenty-five to 50 feet in height, and IJ feet or more in diameter. It is 

 found abundantly throughout the Rocky Mountain region (northern 

 United States, north of boundary, in south central and Pacific coast 

 region,) at elevations between 6,000 and 10,000 feet. The wood is soft, 

 light, weak, and little used except for light fuel and in the manufacture 

 of paper-pulp; the poles occasionally for fencing. 



Beso'iption. — Leaves 1 to 3 inches long, rounded-ovate, short-pointed, somewhat 

 wedge or heart-shaped at the base; smooth on both sides, margin with fine teeth; 

 footstalks slender and flattened at right angles to the plane of the leaf. The bark is 

 chiefly smooth and of a grayish-white color. 



83.— Balsam Poplar. Balm-of-Gilead. Tacamahac. (Populus 



halsamifera^ Linn.) 



A large tree occurring in the Eocky Mountains of Montana and Idaho 

 (it also extends eastward through the Northern States and north of the 

 United States boundary). It generally prefers and thrives best in moist 

 situations along water-courses, often attaining a height of 60 to 81) 

 feet, with a diameter of 3 to 6 feet. The wood is quite similar to that 

 of the Big Cottonwood {Populus monilifera^ Ait.), and a good substitute 

 for it in more northern localities. 



Description. — Leaves ovate, gradually tapering to a point, finely toothed on the 

 margin, smooth above, whitish below. Branches round; large buds, coated with 

 resinous gum, which is sometimes used in officinal preparations. 



Variety candicans, Gray, of this species is found in Colorado, north- 

 ward, and eastward, but is quite unknown in the wild state, being 

 chiefly, if not entirely, introduced in the above range j very common. 

 The wood is considerably heavier than that of the type. 



Description. — Leaves usually larger, heart-shaped, densely white beneath, and with 

 hairy footstalks. 



84.— Black Cottonwood. *' Bitter Cottonwood." {Populus 



angustifolia, James.) 



Eather abundant throughout the Kocky Mountain region (also in 

 southwestern Dakota and eastern Arizona); less common in southern 

 part of its range, but one of the least valuable deciduous trees of the 

 region. It grows in damp situations, along the borders of mountain 

 streams, at elevations between 6,000 and 10,000 feet. A considerably 



