Perennial herb with stout taproot; stems to c. 1 m tall, ± erect, often somewhat flexuous. Petiole much < lamina, the anterior side flattened with raised margins so as to appear concave, sometimes ciliolate. Lamina of lower lvs 6-30 × 1.5-6.5 cm, narrow-lanceolate, oblong or lingulate, ± membranous, strongly undulate with ± crisped margins, minutely puberulent on midrib towards base below; base attenuate; apex acute. Upper lvs similar but much smaller. Infl. branches many, ± erect, often simple; whorls mostly contiguous, the lower sometimes with a small subtending lf, rarely lvs present towards apex. Fls ☿ or unisexual, strongly protandrous, dense. Pedicels slender, minutely puberulent. Perianth 1-2.5 mm long; segments of outer whorl ± elliptic, obtuse, not reflexing at fruiting; segments of inner whorl much longer, greatly enlarging at fruiting. Fruiting valves 3-4.5 × 3-5 mm, broad-ovate to orbicular, sometimes wider than long, strongly reticulate with raised veins, entire, sinuate or crenulate; tubercles 1-3, generally broad-ovoid, ± deep red and often 1 much larger and occupying from ?-1/2 length of valve. Nuts 2-2.5 mm long, dark brown, sharply angled.