Annual or short-lived perennial herb; stems up to 1.5 m tall, basal part creeping and rooting, apical part erect, glabrous or puberulous on upper nodes. Leaves with petiole up to 14 cm long; lamina ovate-cordiform or broadly so, largest (5–)7–14(–35)≈5–10(–15) cm, apex acute to acuminate or drawn out into a short obtuse tip, base rounded to cordate, margin subentire or crenate to sharply dentate, with scattered broad glossy hairs, densest along veins. Panicle open, 5–20(–35) cm long, with dense purple (rarely white) broad glandular hairs, finely puberulous and with long pilose hairs; primary bracts green to purple, ovate to elliptic, from leaf-size down to 5≈3 mm near apex, with long broad glossy purplish (rarely white) hairs, no capitate glands; secondary bracts purple, 3–8≈1–3 mm; pedicels of central flowers 1–4 mm long, of lateral flowers 5–12 mm long. Calyx dark purple (rarely green), glandular-puberulous, finely puberulous and with long pilose hairs; lobes tapering or slightly spathulate, linear-lanceolate, ventral and lateral 7–15 mm long, dorsal 9–16 mm long. Corolla blue or purple with white tube, 15–27 mm long, with long scattered glandular hairs; tube 5–7 mm long; lower lip 10–18 mm long, lobes ± 2 mm long, ovate; anthers 3–4.5 mm long; staminodes ± 5 mm long, puberulous, widened apically. Capsule 17–23 mm long, the valves 2–3 mm wide, glandular-puberulous and with scattered non-glandular hairs. Seed ± 1.5 mm long.
