A tree, 50°—70° high, with a trunk occasionally 3° in diameter, gracefully spreading and ascending branches forming a broad open head of wide-spreading branches, and slender often pendulous branchlets, pale green and glabrous or puberulous when they first appear, soon becoming glabrous, and light yellow during their first season. Winter-buds narrow, acute, light orange-brown, puberulous toward the base of the outer scales, the terminal about ¼′ long, and two or three times as large as the much-compressed oblong lateral buds. Bark pale gray or rarely white, and deeply divided into broad flat ridges. Distribution. Banks of mountain streams; southwestern California (Mill Creek, above Forest Home, San Bernardino Mountains) and southern and central Arizona; widely distributed through northern Mexico (_var. Jonesii_ Sarg.); well distinguished from the other Cottonwoods of the United States by its small fruit. Often planted as a street tree in the towns of southern Arizona. 10. Populus texana Sarg. [Illustration: Fig. 126] Leaves thin, glabrous, broadly ovate, gradually narrowed, long-pointed and acuminate at apex, truncate at base, coarsely crenately serrate below the middle, entire above, 3′—3¼′ long and 2¼′—2½′ wide; petioles slender, compressed, 1½′—2½′ in length. Flowers not seen. Fruit: aments slender, glabrous, 2½′—3′ long; fruit oblong-ovoid, acute, deeply pitted, glabrous, thin-walled, 3-valved, ⅓′ in length; disk slightly lobed; pedicel slender, 1/16′—⅛′ in length; seeds ovoid, acuminate, 1/16′ long. A tree up to 60° high, with a trunk sometimes 3° in diameter, stout more or less pendulous branches and stout glabrous pale yellow-brown branchlets. Winter-buds acuminate, glabrous. In cañons and along the streams of northwestern Texas, where it appears to be the only Cottonwood. 11. Populus McDougallii Rose. [Illustration: Fig. 127] Leaves broadly ovate, abruptly short-pointed or acute at apex, broadly or acutely cuneate or truncate, or on vigorous shoots rarely slightly cordate at base, finely or often coarsely crenately serrate, bluish green, thin, pubescent on the under sides of the midrib and primary veins early in the season, otherwise glabrous, 1½′—3′ long and broad, with slender midribs and veins; petioles slender, slightly compressed, pubescent early in the season, becoming glabrous, 1½′—2′ in length. Flowers not seen. Fruit: aments glabrous, short-stalked, 2′—2½′ long; fruit ovoid and acute at apex to ellipsoidal and acute or acuminate at ends, glabrous, slightly pitted, thin-walled, 3-valved, 5/12′—½′ long; disk not more than ⅛′ in diameter; pedicels glabrous, ⅛′—⅕′ in length; seeds oblong-ovoid, acuminate, ⅛′ long. A tree rarely 90°—110° high, usually much smaller, with erect branches and slender branchlets pubescent or puberulous when they first appear, sometimes becoming glabrous during their first season, and sometimes pubescent during two years.