188 PRACTICAL FORESTRY. 



and southward to Florida, but most abundant in the Mississippi 

 Valley. This species has been extensively planted on the prair- 

 ies, and is still highly recommended as a forest tree, but its 

 merits consist mainly in the facility with which it is propagat- 

 ed, and rapidity of its growth, the wood being very inferior, 

 even for fuel, to some of the other species of this genus. There 

 is a handsome golden-leaved variety of this species, also a weep- 

 ing variety, both handsome little trees. 



P. tremnloides, Michx. Quaking Asp, American Aspen. 

 Leaves roundish, heart-shaped, with a sharp point, and some- 

 what regular teeth, smooth on both sides, with downy margins. 

 The leaf -stalks long and slender, slightly flattened on the sides, 

 which probably accounts for the constant trembling of the 

 leaves, when there is the slightest breeze. A common and 

 well-known tree, both in forests and under cultivation. A 

 widely distributed species, extending entirely across the Con- 

 tinent, through British America to the Pacific, extending north- 

 ward to the Arctic Ocean. Usually in dense groups on moist 

 soils, on high elevations in our mountain ranges. I have found 

 large groves of this species in the Eocky Mountains at an 

 elevation of ten thousand feet. A medium-sized tree, fifty to 

 seventy-five feet, with stem twelve to twenty-four inches in 

 diameter. Bark smooth, hard, and thin, whitish on the out- 

 side, yellow within, quite brittle. Wood white, soft, but of 

 a firm texture, somewhat resembling that of the White Birch, 

 makes good fuel, and a Quacking Asp log will hold fire longer 

 than any other kind of wood I ever tried while camping in the 

 Eocky Mountain regions. The Indians are well acquainted 

 with this property of the Quacking Asp, and in moving their 

 camps, they use a brand or coals of this tree for taking fire 

 from the old to the new. It is also a favorite tree with the 

 beavers for building their dams. 



P. trichocarpa, Torr. and Gray. California Balsam Poplar. 

 Leaves heart-shaped, or ovate to lanceolate, scalloped with 

 rounded teeth, two to four inches long ; stalks an inch or two 

 long ; fertile catkins five or six inches long. Seeds nearly 

 white. A large tree in California, from San Diego northward 

 to British Columbia. In Washington Territory, it is said to 

 grow nearly one hundred feet high, with stem three to six feet 

 in diameter. In low valleys and canyons near streams. 



