Plants perennial, 2–12 dm in terrestrial plants, to 30 dm in some aquatic plants; roots also sometimes arising from proximal nodes; rhizomes or stolons usually present. Stems prostrate to ascending or erect, simple or branched, ribbed, glabrous or strigose to hirsute. Leaves: ocrea tan to dark brown, cylindric or flared distally, 5–50 mm, chartaceous or, sometimes, foliaceous distally, base inflated, margins truncate to oblique, glabrous or ciliate with hairs 0.5–4.5 mm, surface glabrous or appressed-pubescent to hirsute, not glandular-punctate; petiole 0.1–3(–7) cm, glabrous or appressed-pubescent to hirsute, leaves sometimes sessile; blade without dark triangular or lunate blotch adaxially, ovate-lanceolate to elliptic or oblong-lanceolate, 2–15(–23) × 1–6(–8) cm, base usually tapered to acute or rounded, rarely cordate, margins antrorsely scabrous, apex acute to acuminate, faces glabrous or sparingly strigose, midveins glabrous or strigose, not glandular-punctate. Inflorescences terminal, ascending to erect, uninterrupted or interrupted proximally, 10–150 × 8–20 mm; peduncle 10–50 mm, glabrous or strigose to hirsute, often stipitate-glandular; ocreolae overlapping except sometimes proximal ones, margins ciliate with bristles to 1 mm. Pedicels ascending, 0.5–1.5 mm. Flowers bisexual or functionally unisexual, some plants having only staminate flowers, others with only pistillate flowers, 1–3(–4) per ocreate fascicle, heterostylous; perianth roseate to red, glabrous, not glandular-punctate, slightly accrescent; tepals 5, connate ca. 1/3 their lengths, obovate to elliptic, 4–6 mm, veins prominent, not anchor-shaped, margins entire, apex rounded to acute; stamens 5, included or exserted; anthers pink or red, elliptic; styles 2, included or exserted, connate 1/2–2/3 their length. Achenes included, dark brown, biconvex, (2–)2.2–3 × (1.5–)1.8–2.6 mm, shiny or dull, smooth or minutely granular. 2n = 66, 132.
