Plants perennial, glabrous or nearly so, with thick, vertical or oblique rootstock (reaching deep into substrate) and remote 2d-order roots. Stems usually erect, several from base, or occasionally solitary, branched in distal 1/2 (in inflorescence), (30–)40–100(–130) cm. Leaves: ocrea often with fringed margins; blade oblong-lanceolate to lanceolate, 3–12(–15) × 1–3(–5) cm, usually more than 4 times as long as wide, base sagittate or sometimes hastate (with acute lobes directed downward, ± parallel to petiole, or often reflexed outward), margins entire to obscurely and irregularly repand, usually crisped and undulate, occasionally flat, apex acute. Inflorescences terminal, occupying distal 1/3 of stem, usually dense, or interrupted in proximal part, broadly paniculate, pyramidal (1st-order branches usually repeatedly branched, with numerous 2d-order branches). Pedicels articulated near middle, filiform, 2–6(–7) mm, articulation distinct. Flowers (3–)4–8(–12) in whorls; inner tepals orbiculate, occasionally broadly ovate, 2.5–3.5(–4) × 2.5–3.5 mm, base rounded, truncate, or slightly cordate, apex obtuse; tubercles small or occasionally absent. Achenes black or dark brown, 1.5–1.8 × 0.8–1.2 mm, normally smooth. 2n = 14 (pistillate plants), 15 (staminate plants).
