Perennial herb, often with a shrubby habit, erect or decumbent, up to 70 cm. high or more; main stems often woody, terete or indistinctly quadrangular, with a dark brown somewhat rimose bark, glabrous, younger branches somewhat pilose but soon glabrescent, striate, yellowish-brown. Leaves spirally arranged, petiolate; lamina 2·5–5·5 × 1·6–2·8 cm., ovate, ovate-lanceolate or elliptic, usually glabrous on both surfaces, rarely the younger leaves scattered-pilose but soon glabrescent, bright green on the upper, greyish-green on the lower surface, apex acute, margins crenulate-denticulate, base broadly to narrowly cuneate herbaceous; secondary nerves 6–8 pairs; petiole (0·3) 0·6–1 (1·7) cm. long, rather slender, glabrous, eglandular. Flowers solitary, axillary, deep red; bracts up to 5 mm. long, lanceolate, acute, glabrous; pedicel 1·5–3·5 cm. long, very slender, glabrous. Lateral sepals up to 6 × 2·2 mm., oblong-elliptic, apically finely caudate, glabrous or rarely finely puberulous; posterior sepal c. 6 mm. in diam. at the mouth, 2·3–3 cm. long, bucciniform, tapering into the spur, usually glabrous; spur medium-thick, recurved, with the end slightly thickened and sometimes very shortly bifid. Anterior petal c. 6·5 × 7 mm. (when flattened), cucullate, apically produced into a short appendage, dorsally cristate; lateral united petals up to 10 mm. long, deeply 2-lobed, usually glabrous; anterior lobe c. 8 × 4–5 mm., broadly oblique-elliptic to ovate-elliptic, entire; posterior lobe c. 5 mm. long, 2–3 mm. high, very broadly oblique-obovate to transversely semi-elliptic. Ovary glabrous. Capsule not known in a mature state. Seeds numerous.