Distribution. Banks of streams; valley of the upper Sacramento River southward through western California to the San Pedro Mártir Mountains, Lower California; most abundant in the San Joaquin Valley, and ascending the western slopes of the southern Sierra Nevada to altitudes of 3000°.
Often planted in southern California as a shade-tree, and for the fuel produced quickly and abundantly from pollarded trees.
In San Bernardino and San Diego Counties, California, generally replaced by the var. pubescens Sarg., differing in its pubescent branchlets and ranging eastward to southwestern Nevada and southern Utah. In southern Arizona and near Silver City, Grant County, New Mexico, represented by the var. Thornberii Sarg., differing from the typical P. Fremontii in the more numerous serratures of the leaves, in the ellipsoidal not ovoid capsules with smaller disk and shorter pedicels, and by the var. Toumeyi Sarg., differing from the type in the shallow cordate base of the leaves, gradually narrowed and cuneate to the insertion of the petiole, and in the larger disk of the fruit (Fig. 124). The var. macrodisca Sarg. with a broad disc nearly inclosing the ellipsoidal fruit is known only in the neighborhood of Silver City.
× Populus Parryi Sarg., a probable hybrid of P. Fremontii and P. trichocarpa, with characters intermediate between those of its supposed parents, grows naturally along Cottonwood Creek on the west side of Owens Lake, Inyo County, and in the neighborhood of Fort Tejon, Kern County, and as a street tree is not rare in San Bernardino, California.
9. [Populus arizonica] Sarg. Cottonwood.
Populus mexicana Sarg., not Wesm.
Leaves deltoid or reniform, gradually or abruptly long-pointed at the acuminate entire apex, truncate or broad-cuneate at the wide base, finely serrate with numerous teeth, as they unfold dark red covered below with pale pubescence, pubescent above, ciliate on the margins, thin, glandular with bright red caducous glands, soon becoming glabrous, at maturity subcoriaceous, bright yellow-green, very lustrous, 1½′—2′ long and broad, with a slender yellow midrib and obscure primary veins; petioles laterally compressed, sparingly villose when they first appear, soon glabrous, 1½′—2′ long; leaves on vigorous leading shoots often rounded at apex, cuneate at base, and often 2′ long and 3′ wide, with petioles often 3′ in length. Flowers: staminate aments dense, cylindric, 1—1½′ long, the pistillate slender, many-flowered, 1½′—2′ long, becoming 3′—4′ long before the fruit ripens; disk of the staminate flower broad-oblong; stamens numerous; disk of the pistillate flower deep cup-shaped, nearly entire; ovary ovoid, rounded at apex, slightly 3 or 4-angled, short-stalked, nearly inclosed in the cup-shaped membranaceous disk. Fruit on short stout pedicels, round-ovoid, buff color, slightly 3 or 4-lobed, deeply pitted, thin-walled, about ¼′ long.
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.