Polygonum tenue Michx.
Family: Polygonaceae
Pleat-Leaf Knotweed,  more...
Polygonum tenue image
Herbs. Stems erect, green or brown-ish, simple or branched from below middle, not wiry, 5-50 cm, glabrous or papillose-scabridulous. Leaves uniformly distributed, articulated to ocreae, basal leaves caducous or persis-tent, distal leaves abruptly reduced to bracts; ocrea 6-15 mm, glabrous or papillose-scabridulous, proximal part cylindric, distal part soon disintegrating into a few brown fibers; petiole 0.1-1 mm; blade 1-veined, with 1 pleat on each side of midrib, narrowly lanceolate to linear, 25-40 × 1-8 mm, margins usually flat, papillose-denticulate, apex mucronate or cuspidate. Inflorescences axillary and terminal, spikelike, slender, elongate; cymes spaced along branches, 1-2(-3)-flowered. Pedicels enclosed in ocreae, erect, 1-1.5 mm. Flowers closed; perianth 2.5-4.2 mm; tube 15-22% of perianth length; tepals overlapping, green, often brownish when dried, with pink or white margins, petaloid or sepaloid, elliptic, cucullate, navicular, apex rounded; midveins usually unbranched, rarely branched; stamens 8. Achenes enclosed in or slightly exserted from perianth, black, elliptic to oblong, 2.3-4 mm, faces subequal, shiny, smooth or minutely striate-tubercled near edges and apex. 2n = 20. Flowering Jun-Oct. Dry acid soils in exposed sites; 100-1000 m; Ont.; Ala., Ark., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis., Wyo.
Slender annual, 1-4 dm, with ascending or erect branches; lvs linear, 1-3 cm, subulate-tipped, minutely spinulose-serrulate, plicate in 2 folds near the midvein; fls remote, mostly only 1 per ocrea; perianth deeply cleft, the oblong segments connivent over the achene; achene black, sharply trigonous, 2.5-4 mm; 2n=20, 30, 32. Dry, chiefly acid soils; Me. to Minn., s. to Ga. and Tex.

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

©The New York Botanical Garden. All rights reserved. Used by permission.
From Flora of Indiana (1940) by Charles C. Deam
This species prefers a slightly acid soil and is generally found in exposed places without ground cover and where there are very few or no other plants. In the lake area it is generally found on the crests, slopes, and bases of black and white oak ridges. South of the lake area it is generally found on sandstone bluffs, on exposed crests of chestnut oak ridges, and in sandy places similar to those in the northern part of the state.