8. Populus Tremuloides Michx. American Aspen. Quiver-Leaf

Fig. 1447

Populus tremuloides Michx. Fl. Bor. Am. 2: 243. 1803.

A slender tree, with smooth, light green bark, reaching a maximum height of about 100° and a trunk diameter of 3°, the young foliage glabrous, excepting the ciliate margins of the leaves. Petioles very slender, flattened laterally, causing the leaves to quiver in the slightest breeze; leaves broadly ovate or orbicular, short-acuminate at the apex, finely crenulate all around, truncate, rounded or subcordate at base, 1'-2 1/2' broad, or those of very young plants much larger; bracts silky, deeply 3-5-cleft into linear lobes; aments drooping, the staminate 1 1/2-2 1/2long, 3"-4" in diameter, the pistillate longer, dense; stigma-lobes linear; capsule like that of the preceding species, but somewhat smaller.

In dry or moist soil, Newfoundland to Hudson Bay and Alaska, New Jersey, Pennsylvania, Kentucky, Nebraska, in the Rocky Mountains to Mexico and to Lower California. Ascends to 3000 ft. in the Adirondacks. American, trembling or white poplar. Quaking or mountain asp. Wood soft, weak, light brown; weight per cubic foot 25 lbs. March-May.

9. Populus Nigra L. Black Poplar. Willow Poplar

Fig. 1448

Populus nigra L. Sp. PL 1034. 1753.

A large tree, sometimes 100° tall and the trunk 40 in diameter, usually much smaller. Twigs terete; young foliage somewhat pubescent, the mature leaves firm, nearly or quite glabrous; petioles slender, flattened laterally; leaves broadly deltoid, abruptly acuminate at the apex, broadly cuneate or obtuse at the base, crenate, 2-4' long; staminate aments 1'-2' long; stamens about 20; pistillate aments 2'-5' long in fruit, spreading; capsules oblong, very obtuse, borne on pedicels of much less than their own length.

Valleys of the Hudson and Delaware Rivers, naturalized from Europe. Cat-foot poplar. Devil's-fingers. Old English poplar. April-May.

The Lombardy poplar (Populus italica Moench (Populus dilatdta Ait.), commonly planted for ornament, occasionally spreads by sending up shoots from its subterranean parts. Poplar-pine.

10. Populus Deltoides Marsh. Cottonwood. Necklace Poplar

Fig. 1449

Populus deltoides Marsh, Arb. Am. 106. 1785. Populus carolinensis Moench, Verz. PL 81. 1785. Populus monilifera Ait. Hort. Kew. 3: 406. 1789. Populus angulata Ait. Hort. Kew. 3: 407. 1789.

A large tree, the greatest of the poplars, attaining a maximum height of 1500 and a trunk diameter of 7 1/2°, the bark grayish-green somewhat rough when old. Foliage glabrous; leaves broadly deltoid-ovate, abruptly acuminate at the apex, crenulate, truncate at the base, 4'-7' long; petiole flattened laterally, stout, about as long as the blade; bracts glabrous, deeply fimbriate; staminate aments drooping 3'-5' long, 5"-6" in diameter; pistillate aments loosely flowered, becoming 6'-10' long in fruit; capsules ovoid, acute, 4"-s" long, 2-4-valved, shorter than or equalling their pedicels.

In moist soil, especially along streams and lakes, Quebec to Manitoba, south to Connecticut, Florida and Tennessee. Wood soft, weak, dark brown; weight per cubic foot 24 lbs. April-May. Carolina poplar. Water- or river-poplar. Berry-bearing, or black Italian poplar. Big or yellow cottonwood. Cotton-tree.

Alamo. The species consists of several races.