Upright or sometimes straggling caulescent herb, 10–30(–60) cm tall. Stems succulent, reddish, often strongly swollen at the base where up to 2 cm diameter, often branching above the base, spreading-pubescent particularly when young. Leaves opposite, pairs subequal; blade somewhat fleshy, ovate-elliptic, 1.5–6.5 cm long, 0.8–4 cm wide, base asymmetrically rounded or subcordate to shortly attenuate, margin entire, apex acute to subacuminate, surfaces densely pubescent particularly on the nerves beneath, rarely more sparsely so; lateral nerves 7–11 pairs; petiole 1–2(–3.5) cm long, densely pilose. Inflorescence axillary, solitary, 3–10-flowered; peduncle 3–10(–15) cm long, pubescent towards the base, largely glabrous towards the apex; pedicels fine, 10–20 mm long, glabrous or with scattered eglandular and/or glandular hairs, rarely pubescent; bracts linear, 1–2 mm long, pubescent, often early caducous. Calyx lobes purplish, ovate-lanceolate, 2–3 mm long, sparsely pubescent, occasionally with glandular hairs, with or without scattered subsessile glands. Corolla pale mauve or whitish, rarely purple, usually striped with dark pink to purple lines, 12–20 mm long; tube 6–9 mm long, strongly ventricose on the floor above the middle where 3–4 mm deep, glandular-pilose outside, papillose within below the origin of the stamens and at the mouth; limb bilabiate, oblique; upper lip of two erect, rounded lobes 2–3 mm long and wide, lower lip 6–11 mm long, protruding, the three lobes spreading, usually oblong-rounded, 3–6 mm long, 3–4.5(–6) mm wide, palate curved upwards, weakly ridged so that the mouth is open but vertically compressed. Stamens arising from the upper half of the corolla tube; filaments 2–3 mm long, straight, glabrous; anther thecae divergent, ± 0.8 mm wide; staminodes minute. Ovary cylindric, 4.5–6 mm long, glabrous except for scattered subsessile glands, rarely sparsely pubescent; style 1.5–3 mm long, glabrous; stigma capitate, ± 0.4 mm wide, papillose. Capsule 20–45 mm long, 1.5–2 mm diameter, glabrous. Seeds 0.4–0.6 mm long, verruculose with slight longitudinal ridging. Fig. 2, p. 17.
