POPULUS HETEROPHYLLA Linnæus. Swamp Cottonwood. (× 1/2.)
POPULUS DELTOIDES Marshall. Cottonwood. (× 1/2.)
Remarks.—The cottonwood is adapted to a moist soil, propagates easily, grows rapidly and is one of the best trees for forestry purposes for planting overflow lands, and for planting where a quick shade is desired or for temporary windbreaks.
The leaves of this tree are quite variable and several forms have been described. The Carolina poplar of nurserymen has an upright habit of growth and was formerly much planted as a shade tree. Its undesirable qualities have condemned it, and most cities now prohibit its planting.
Cottonwood has many uses, and was formerly a very important timber tree, but the supply has so diminished that large trees have become quite scarce. The thick bark was much used by the boys of the pioneers for whittling out toys, etc.
4. Populus grandidentàta Michaux. Large-toothed Aspen. [Plate 18.] A small or medium-sized tree, 1-4 dm. in diameter; bark smooth, grayish-green or whitish, becoming furrowed and dark brown on the trunks of old trees that grow in the northern part of the State, especially when growing in a swampy habitat. In the southern part of the State where the tree usually grows on the top of hills, the bark does not darken so much, frequently remaining a light to dark gray until maturity. Shoots more or less woolly at first, becoming glabrous, reddish-brown; leaves on sprouts and very young trees very velvety beneath, slightly hairy above, ovate in outline, cordate at base and with blades up to 20 cm. in length; leaves on older trees a yellow green, glabrous, ovate, blades usually 6-10 cm. long, coarsely and unevenly toothed, the base slightly rounded, rarely truncate or slightly cordate, the apex pointed or rounded; petioles strongly flattened laterally; stamens 6-12; capsule about 5 mm. long on a stalk about 1 mm. long; wood soft, light and not strong.