Perennial herb; taproot thick; stems many, spreading, to c. 60 cm tall. Petiole of lower lvs long and often > lamina, often puberulent. Lamina of lower lvs 3-20 × 1-8 cm, with basal 1/4 of lamina forming 2 large rounded cordate lobes with a rounded sinus at the junction with remainder of lamina and thus lf constricted in basal 1/2, flat, occasionally simple, oblong, puberulent towards base beneath; apex obtuse to rounded. Upper cauline lvs much smaller, simple, oblong, entire, with cuneate base. Infl. branches spreading at a wide angle at flowering, later becoming twisted and forming a tangled mass. Whorls of fls distant; subtending lvs present to the branch apex, reduced, narrow-linear, < 1 cm long; pedicels slender, ciliolate. Fls ☿, strongly protandrous. Perianth 1-2 mm long, often reddish; segments of outer whorl ± ovate-oblong, not reflexed at fruiting; segments of inner whorl becoming much elongated. Fr. valves 4.5-5.5 mm long, triangular, often narrowly so, with thick, raised reticulations; apex obtuse; marginal spines to 2 mm long, thick; tubercles unequal but prominent on each valve, oblong. Nut 1.8-3 mm long, deep shining brown, acutely angled.