Leafl. Bot. Observ. Crit. 1: 24. 1904.
Plants annual, 3–15(–20) dm; roots also rarely arising from proximal nodes; rhizomes and stolons absent. Stems erect, branched distally, ribbed distally, hirsute proximally, stipitate-glandular distally, usually smooth proximally. Leaves: ocrea brownish to reddish brown, cylindric, 8–20 mm, chartaceous, base inflated or not, margins truncate, ciliate with bristles 2–7 mm, surface strigose to hirsute, not glandular-punctate, rarely stipitate-glandular; petiole (0.1–)0.5–1.5 cm, hirsute, leaves sometimes sessile; blade without dark triangular or lunate blotch adaxially, narrowly lanceolate, 6–18 × 1–3.5 cm, base tapering, margins antrorsely strigose, apex acuminate to attenuate, faces sparingly hirsute abaxially and adaxially, veins often hirsute, sometimes stipitate-glandular. Inflorescences terminal and axillary, nodding or drooping, usually interrupted, 10–100 × 5–10 mm; peduncle 20–50 mm, stipitate-glandular; ocreolae overlapping or not overlapping proximally, margins eciliate or ciliate with bristles to 1.3 mm. Pedicels ascending to spreading, 1–4 mm. Flowers (1–)2–8 per ocreate fascicle, homostylous; perianth roseate or purple, glabrous, not glandular-punctate, scarcely accrescent; tepals 5, connate in proximal 1/3, obovate, 2.4–3.2 mm, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded; stamens 5 (or 8), included; anthers pink, elliptic; styles 2, connate to middle. Achenes included, dark brown to black, biconvex, 1.8–2.5 × 1.5–2 mm, shiny, smooth.
Phenology: Flowering Jul–Oct.
Habitat: Low thickets, swamps, bogs, moist shorelines, clearings, recent burns, cultivated ground
Elevation: 0-300 m
N.B., Ont., Que., Conn., Del., Fla., Ill., Ind., Ky., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., Ohio, Pa., R.I., Vt., Va., Wis.
An infusion made from entire plants of Persicaria careyi was used by the Potawatomi as a cold remedy and febrifuge (D. E. Moerman 1998).