187 



POrLAES. 



82. — Quaking- Aspen or Asp. American Aspen. (Populm 



tremuloidcs, Micliaux.) 



One of tbe 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 (ires, thus furnisLing tbe neces- 

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

 Twenty-live to 50 feet in height^ and 1^ feet or more in diameter. It is 

 found abundantly thronghout 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, w^eak, and little used except for light fuel and in the manufacture 

 of paper pulp; the poles occasionally for fencing. 



Description. — Leave.s 1 to 3 iDcLcs long, romided-ovatc, sliort-pointed, somewhat 

 wedge or beart-sliaped 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 

 chieiiy smooth and of a grayish- white color. 



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



halsamifera, Linn.) 



A large tree occurring in theEocky 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 heigiit of GO to 80 

 feet, witli a diameter of 3 to 0 feet. The wood is quite similar to that 

 of the Big Oottoiiwood (Populus monilif era, Ait.), and a good substitute 

 for it in more northern localities. 



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

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

 resinous gum, which is sometimes used in officinal prepai'atious. 



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

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

 cliiefly, if not entirely, introduced in the above range; very common. 

 The wood is considerably heavier than that of the type. 



Description. — Leaves usually larger, heart-shaped, densely ivhite heneath, and with 

 hairy footstalks. 



84. --BLACK COTTOiSfWOOD. " BiTTER COTTONWOOD." (PopulllH 



angustifoUa, James.) 



Eather abundant througliout the Eocky 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 mountaiu 

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



