Polygonum erectum L.
Source: USDA Plants_111306
Family: Polygonaceae
Erect Knotweed
[Polygonum aviculare var. erectum (Roth) Meisn.]
Polygonum erectum image
Plants light green or yellowish, heterophyllous. Stems erect to ascending, sparingly branched in distal 2, not wiry, 15-75 cm. Leaves: ocrea 7-12 mm, proximal part cylindric, distal part usually persistent, with strong veins, margins entire or lacerate, silvery, later disintegrating into ± persistent brown fibers; petiole 1-5 mm; blade light green or yellowish, elliptic to obovate, 30-60(-80) × (8-)10-25 mm, margins flat, apex obtuse; stem leaves 1.5-3.5(-4) times longer than branch leaves; distal leaves overtopping flowers in distal part of inflorescence. Inflorescences axillary; cymes in axils of most leaves and toward tips of stems and branchs, 1-5-flowered. Pedicels mostly exserted from ocreae, 3-7 mm. Flowers closed; perianth 2.8-3.8(-4.2) mm; tube 20-37% of perianth length; tepals overlapping, green with yellowish, rarely whitish green, margins, sepaloid, not keeled, oblong to obovate, cucullate; midveins branched, moderately to heavily thickened; stamens 7-8. Achenes enclosed in perianth, brown to tan, ovate, 3-gonous, 2.3-3.5 mm, faces subequal, ± concave, apex not beaked, edges concave, dull, striate-tubercled; late-season achenes uncommon, 4-5 mm. Flowering May-Oct. Dry, waste ground; 10-300 m; Alta., Ont., Que., Sask.; Ala., Ark., Colo., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo. Polygonum erectum was cultivated in the midwest by Native Americans for its starchy seeds (C. M. Scarry 1993). It was formerly confused with P. achoreum (T. R. Mertens and P. H. Raven 1965).

Much like no. 3 [Polygonum achoreum S. F. Blake], but somewhat heterophyllous (more so in age), with green or bright yellow-green lvs, the larger ones mostly 25-60 נ10-30 mm; ocreae hyaline-silvery, entire to slightly lacerate; perianth cleft ca 3/4 its length; achenes light to dark brown, striate-papillose. A weed in waste places, widespread (but not common) in the U.S. and s. Can.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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From Flora of Indiana (1940) by Charles C. Deam
This species has been reported from all parts of the state, and no doubt is generally distributed. Since this section of the genus has been divided, however, some of the reports doubtless belong to other species. Most authors give the habitat as rich soil about dwellings and in waste places. With one exception, all of my specimens were found in moist, open woodland, usually in hard, clay soil.