Perennial herb with numerous stems from creeping and branched rhizomes, forming large clumps; stems ascending to erect, to 1 m tall, rounded (but triangular at nodes), glabrous but for thin lines of hairs at nodes. Leaves in whorls of 3, with pale yellow sessile glands; petiole pubescent-ciliate, up to 7 mm long; lamina ovate, abruptly narrowed to truncate above a decurrent wavy base, largest 8–9.5≈3–4 cm, apex acute to subacuminate with obtuse tip, margin crenate-dentate, wavy, above glabrous, beneath pubescent along midrib and larger veins. Racemes dense, pyramidal in flower, elongating and cylindrical in fruit, 6–18(–23) cm long; peduncle 0–12 mm long, glabrous; axis finely puberulous; bracts lanceolate to narrowly elliptic, 1–2 cm long (lowermost pair sometimes foliaceous), glabrous, with sessile glands; pedicels 1–2 mm long, glabrous; bracteoles linear-lanceolate, 1.5–2 cm long, ciliate apically. Dorsal and two ventral sepals linear-lanceolate, 1.5–1.8 cm long, ciliate apically, two lateral similar, ± 5 mm long. Corolla pale mauve on the outside, dark velvety vine-red on the inside, 3.5–3.8 cm long, glabrous on the outside; tube ± 2.5 cm long, with inner band of hairs ± 5 mm above base; upper lip slightly hooded, 1–1.3 cm long, lateral lobes in lower lip spreading, elliptic, 0.8–1 cm long, median lobe deflexed, broadly ovate, 1.2–1.5 cm long. Stamens held under upper lip; filaments 1.5–2 cm long, glabrous; anthers ± 1.5 mm long, crisped-puberulous; ventral stigma lobe reduced. Capsule ± 1.2 cm long. Seed pyriform, 1.5–2 mm long.
