Shrubby herb or shrub, forming large bushes or ± scandent; stems up to 1.5(–3) m long, with transverse bands of hairs at upper nodes, otherwise glabrous. Leaves opposite; petiole up to 3 cm long, pubescent adaxially; lamina ovate to elliptic, abruptly narrowed into a decurrent base or attenuate, largest 5–11≈2.5–4 cm, apex acuminate to cuspidate with acute or obtuse tip, margin entire to crenate, subglabrous to crisped-puberulous, densest along veins. Racemes dense and subcapitate in flower, elongating in fruit, 1–6 cm long; axes glabrous to puberulous; peduncle 0–1(–1.5) cm long, glabrous; bracts oblanceolate or narrowly so, 8–15 mm long, puberulous on midrib and ciliate, ± scattered peltate glands; pedicel 0.5–1(–2) mm long, glabrous or puberulous; bracteoles linear-lanceolate, 9–13 mm long, crisped-ciliate. Dorsal and two ventral sepals linear-lanceolate, 9–12 mm long, ciliate, lateral sepals similar or narrowly triangular, 1.5–4 mm long. Corolla dark blue, bluish violet, purple or dark purple, with 4 white bosses on lower lip, 2–3.3 cm long, glabrous outside; tube 1.6–2 cm long, campanulate above, glabrous inside but for band of hairs 3–4 mm above base; upper lip hooded or ± flat, entire or emarginate, 6–15 mm long; lateral lobes of lower lip spreading, obovate-spathulate, 5–10 mm long, median lobe deflexed, broadly oblong, 8–13 mm long. Stamens held under upper lip; filaments 8–20 mm long, glabrous; anthers ± 1.5 mm long, crisped-puberulous; stigma lobes similar. Capsule 8–10 mm long. Seed pyriform, reticulate, 1.5–2 mm long. Fig. 4, 10–15, p. 22.