Slender, erect, glabrous annual 20–70 cm high. Short non-flowering shoots with leaves in whorls of 3, elliptic to ovate, 0.6–1 cm long, 1.5–2.5 mm wide; flowering shoots with erect, alternate leaves, linear, 1–4 cm long, 0.5–1 mm wide. Inflorescence few–many-flowered, at first short and dense, elongating in fruit; bracts 2–4 mm long; pedicels 3–6 mm long. Sepals fused only at base, 3–4 mm long; corolla 6–9 mm long, purple-violet with whitish pubescent palate closing mouth, spur backwards-directed from tube, 7–9 mm long, upper lip pointed outwards with 2 narrow elongate lobes, lower lip shorter with recurved lobes. Capsule with 2 globose lobes, 2.2–2.5 mm long; seeds fimbriate. Flowers spring.