Perennial, semi-succulent, aromatic herb up to 40(–60) cm tall, branched, producing ovoid tubers up to 4(–8) cm long; stem erect to decumbent, 4-angled, shortly pubescent. Leaves opposite, simple; stipules absent; petiole 2–3 cm long; blade ovate, 2.5–8 cm × 2–5 cm, cuneate at base, obtuse to acute at apex, margin crenate-dentate, puberulous and gland-dotted below, distinctly veined. Inflorescence a terminal and slender false spike up to 15 cm long, consisting of compact, sessile dichasia. Flowers bisexual, zygomorphous; pedicel up to 1(–2) mm long; calyx campanulate, 1.5–3 mm long, glandular-hispid, upper tooth ovate, 2 lateral teeth small, 2 lower teeth almost completely fused; corolla 4–8 mm long, pubescent and gland-dotted, with curved tube, 2-lipped, upper lip erect, 4-lobed, whitish, lower lip boat-shaped, bluish purple; stamens 4, shortly united at base, curved within the lower corolla lip; ovary superior, 4-celled, style 2-fid. Fruit consisting of 4 nutlets, but rarely developing. |