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Published In: Flora Boreali-Americana (Michaux) 2: 243. 1803. (Fl. Bor.-Amer.) Name publication detailView in BotanicusView 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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3. Populus grandidentata Michx. (large-toothed aspen)

Pl. 553 a, b; Map 2569

Plants trees 8–20 m tall, relatively open (but sometimes slender in aspect), widely branched with mostly spreading to loosely ascending branches. Bark light gray, relatively smooth, developing darker, roughened cross-ridges, becoming dark brown and longitudinally ridged and furrowed only near the base of older trees. Twigs slender to moderately stout, reddish brown, becoming gray with age, sparsely to moderately pubescent with gray, cobwebby to somewhat woolly hairs when young, becoming glabrous or nearly so with age, the pith white. Winter buds 3–8 mm long, reddish brown, dull, not or only slightly resinous, cobwebby-hairy when young, becoming glabrous or nearly so with age. Leaves heterophyllous (the blades of early-season leaves with fewer, coarser teeth than those developing later in the season), the petiole half as long as to about as long as the blade, noticeably flattened on the sides, at least toward the tip, glabrous or sparsely hairy at the tip. Leaf blades (2–)4–10(–20) cm long, ovate, longer than wide, tapered to a sharply pointed tip, broadly angled or broadly rounded to more commonly truncate at the base, the margins lacking a pale yellow or translucent line or band (viewed under magnification), glabrous or sparsely to moderately pubescent with silky hairs, finely to coarsely scalloped or toothed, mostly with 5–14 relatively coarse teeth 0.5–5.0 mm deep (early-season) or 15–60 finer scallops or teeth 0.5–2.0 mm deep (late-season) per side, the teeth spreading or incurved at their tips but not strongly thickened, often also with 2(–4) shallowly cup-shaped glands at or near the base, the upper surface dark green, glabrous and usually shiny, the undersurface pale green and usually somewhat glaucous, glabrous or sparsely pubescent with white, silky hairs. Inflorescences 5–10 cm long (the pistillate ones elongating to 7–14 cm at fruiting), the bracts deeply cut into 3–7 narrow, deep lobes, the margins silky-hairy, the undersurface glabrous. Staminate flowers with 6–12 stamens. Pistillate flowers with usually 2 carpels, the style branched above the midpoint, the stigmas linear and often deeply 2-lobed (then sometimes appearing as 4 stigmas). Fruits 3–6 mm long, ovoid, glabrous, with usually 2 valves. 2n=38. March–May.

Uncommon, known thus far from northeasternmost Missouri and a single disjunct population in Phelps County (northeastern U.S. west to North Dakota and Missouri; Canada). Mesic upland forests (mostly in openings and along edges), mostly near heads of ravines, and tops of low bluffs.

There has been debate on whether the Missouri populations represent escapes from cultivation or native occurrences that are relictual from past times when the climate was cooler (Steyermark, 1963; Kurz, 2003). However, the species is not commonly planted in Missouri and even the Phelps County population appears to be part of a native plant community without evidence of nearby old homesites. The Missouri Natural Heritage Program tracks the taxon as being of conservation concern in the state. Thus large-toothed aspen is treated as a native member of the flora in the present work.



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