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Published In: Arbustrum Americanum 106. 1785. (Arbust. Amer.) Name publication detailView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 9/22/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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2. Populus deltoides W. Bartram ex Marshall (cottonwood, eastern cottonwood, southern cottonwood)

Pl. 553 h–k; Map 2568

Plants trees 15–35 m tall, relatively open, widely branched with mostly spreading to loosely ascending branches. Bark light to dark brown, with a network of coarse, longitudinal ridges and deep furrows. Twigs slender to more commonly stout, yellowish brown to reddish brown, becoming tan or gray with age, glabrous or sparsely pubescent with short, spreading to somewhat curved, white hairs, the pith white. Winter buds 6–18 mm long, greenish yellow, strongly sticky with yellowish resin, glabrous or sparsely spreading-hairy. Leaves somewhat heterophyllous (the early-season leaves with fewer, deeper teeth than those produced later), the petiole about as long as the blade, noticeably flattened on the sides, at least near the tip, glabrous or hairy. Leaf blades 3–12(–14) cm long, more or less triangular to broadly ovate-triangular, noticeably wider than long to slightly longer than wide, broadest near the base, abruptly tapered to a sharply pointed tip, truncate to broadly cordate at the base, the margins minutely pubescent with moderate to dense, curved hairs, with a well-defined, narrow, pale yellow or translucent line or band (viewed under magnification), finely and unevenly scalloped or bluntly toothed, the teeth mostly 5–20 and relatively coarse (early-season) or 20–50 finer (late-season) per side, these 0.5–7.0 mm deep, incurved and minutely thickened at their tips, sometimes also with 1–6 club-shaped gland(s) at or near the base, the upper and undersurface grayish green to bright green, glabrous. Inflorescences 5–18 cm long (the pistillate ones elongating to 10–24 cm at fruiting), the bracts deeply cut into 9 to numerous irregular lobes, the margins glabrous, the undersurface glabrous. Staminate flowers with mostly numerous (40 or more) stamens. Pistillate flowers with 3 or 4 carpels, the style variously unbranched nearly to the tip or branched nearly to the base, the stigmas flattened. Fruits 6–13 mm long, ovoid, glabrous, with 3 or 4 valves. 2n=38. March–May.

Scattered nearly throughout the state, most abundant in counties bordering large rivers (nearly throughout the U.S. except for some far-western states; Canada, Mexico). Bottomland forests, banks of streams and rivers, margins of ponds and lakes, sloughs, swamps, marshes, and bottomland prairies; also ditches, strip mines, quarries, railroads, roadsides, and moist disturbed areas.

Cottonwood is a fast-growing, large, stately tree that can attain massive trunk diameters. It is cultivated as a shade tree and for erosion control and mine reclamation, but is considered a relatively short-lived species.

Two hybrids that are sometimes also planted in Missouri have been recorded as uncommon escapes (Steyermark, 1963; Eckenwalder, 1977a). Carolina poplar, P. ×canadensis Moench is a hybrid between P. deltoides and the nonnative P. nigra. It is known thus far from historical collections from Iron and Washington Counties. This hybrid has the more columnar growth form of its Lombardy poplar parent and also has early-season leaves that are somewhat longer than wide, with more numerous, finer teeth along the margins than in P. deltoides. It is usually a staminate clone that reproduces vegetatively from root sprouts. Balm-of-Gilead, P. ×jackii Sarg. (P. ×gileadensis Rouleau) is a mostly sterile hybrid between the cultivated P. balsamifera L. and P. deltoides. In Europe it is cultivated for its winter bud resins. It usually occurs as a pistillate clone that reproduces vegetatively from root sprouts. In Missouri, this hybrid is known thus far from historical collections from Reynolds and St. Louis Counties. It differs from P. deltoides in its petioles that are not or only slightly flattened laterally and in its more narrowly ovate leaf blades with somewhat rounded bases.

Eckenwalder (1977a, b) treated the P. deltoides complex as consisting of three intergrading subspecies, two of which are found in Missouri. The third subspecies, ssp. wislizeni (S. Watson) Eckenwalder (Rio Grande cottonwood) occurs in the western United States and adjacent Mexico. It is most similar to ssp. deltoides, differing from that subspecies in its leaf blades mostly lacking basal glands and its sparsely hairy winter buds.

 


 

 
 
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