Bushy, much-branched suffruticose perennial 60-120 cm, rush-like and resembling the habit of some species of Equisetum. Branches bright green, verticillate below, opposite above, spreading and often arching. Stems slender, especially above, glabrous, 4-12-angled, with prominent ridges on angles and striations between. Leaves soon caducous; lower ones in whorls of 3-6, ovate to elliptic, 8.5-15 x 6-9 mm, acute, with one or few large teeth per side; upper leaves smaller, opposite, linear, entire; leaf surfaces glabrous, with a few resinous dots. Petioles 3-4 mm, often persistnt and adpressed to stem. Inflorescences opposite or whorled, borne at ends of ultimate branches; cymes 1-2-flowered. Bracteoles linear, small, with few resinous dots. Peduncles 3-4 cm; pedicels 1-1.5 cm. Calyx lobes 2-3 mm, acute or mucronate, glabrous. Corolla coral-red or scarlet, 15-25 mm, glabrous both outside and within; dorsal lobe deeply emarginate, 3 ventral lobes subequal to dorsal lobe, Stamens to 18 and 20 mm, reaching mouth of corolla tube; filaments glabrous. Style to 18 mm. Capsule globose, 3-6 mm diam., filled with white hairs. Seeds pale brown, ovoid, verrucose.