Moderately or sparsely branched perennial to 130 cm. tall, though usually less; stem erect to slightly decumbent, finely pubescent at first but soon glabrescent.. Leaves spirally arranged; petiole (0.4–)0.8–6.5(–8) cm. long, slender, finely pubescent or glabrous; lamina elliptic to ovate-elliptic or oblong-elliptic, (2–)3–13(–16) cm. long, (1.4–)1.8–5.5(–6.2) cm. broad, the apex acuminate, acute, the base shortly cuneate into the petiole, sparsely pubescent on both surfaces or subglabrous, or glabrescent beneath; lateral veins (6–)7–11 pairs; margin shallowly crenulate or crenate-dentate.. Flowers solitary or more usually in fascicles of 2–4, epedunculate, deep red with white or creamish anthers, more rarely pinkish or whitish, the lateral united petals often with a yellowish zone in the centre.. Bracts linear-subulate, 2–4 mm. long, inconspicuous.. Pedicels 3.2–7.5 cm. long, slender, pubescent or glabrous.. Lateral sepals 2, ovate to ovate-oblong, 7–12 mm. long, 2.5–5 mm. broad, acuminate, often patent.. Lower sepal narrowly bucciniform, 9–18 mm. long, gradually tapering into an incurved spur, 22–40 mm. in length overall, glabrous, the tip slightly swollen, slightly or conspicuously bilobed.. Dorsal petal 8–17 mm. long, 5–12 mm. broad, cucullate, dorsally with a narrow crest terminating in a short acute point.. Lateral united petals 10–17 mm. long, the upper petal of each pair slightly larger than the lower; upper petal obliquely oblong or oblong-elliptic, 6–9 mm. long, 4.5–5.5 mm. broad; lower petal ± oval, 4.5–9 mm. long, 3–4 mm. broad, slightly apiculate towards the top along the inner margin.. Ovary glabrous.. Fruit narrowly to broadly fusiform, 13–22 mm. long, 4–8 mm. broad, glabrous.. Fig. 4/62, p. 8.