Populus deltoides Marshall
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Tall tree with ± spreading branches and a broad crown, the bark becoming deeply furrowed and nearly black; terminal buds glabrous, viscid; petioles strongly flattened; lvs glabrous, typically broadly deltoid, 8–14 cm, nearly as wide, short-acuminate, broadly truncate or subcordate at base, serrate with incurved, callous-tipped teeth (the largest teeth mostly 2–5 mm deep), generally bearing 2–5 prominent glands on the upper side at the very base; lowest lateral veins of the lvs widely spreading; scales of the catkins fringed; floral disk 1.5–4 mm wide; stamens (30–)40–80; stigmas 3 or 4, broadly dilated; frs ovoid, 3–4- valved, 6–10 mm, on pedicels 3–10 mm, forming a loose raceme; seeds (3–)7–10(–18) per placenta; 2n=38. Low woods and moist prairies and river-banks; Que. and N. Engl. to Fla. and Tex., and w. to the base of the Rocky Mts. Var. deltoides, the eastern cottonwood, widespread in our range, has gray or reddish-brown twigs, glabrous winter-buds, and mostly 3–5 glands at the base of the lvs, the lvs of the short shoots with mostly 15–30 teeth per side. The wholly confluent var. occidentalis Rydb., the Great Plains cottonwood, forming gallery forests along the rivers across the plains, and encroaching into the westerly Great Lakes region, has yellowish twigs, finely pubescent winter buds, mostly only 2 basal glands on the lvs, and mostly only 5–15 teeth on each side of the often more deltoid-ovate and more long-acuminate lvs. (P. sargentii; P. deltoides ssp. monilifera)