Annual erect herb up to 50 cm. tall. Stem slender, sometimes woody at the base, usually branched from the base, rarely unbranched or branched at the apex only, 4-ridged. Leaves thin, not fleshy; lamina 10–30 (40) x 2–7 (20) mm.; cauline ones lanceolate, attenuate at the base into a short petiole, acute or subacute at the apex, patent; basal ones, ovate-elliptic to broadly elliptic, the uppermost shorter and narrowing passing to bracts. Flowers 5-merous, pale blue (whitish in dried material) in terminal few- or many-flowered corymbiform cymes, pedicellate; pedicels very variable. Calyx divided to the base; segments 1–4 x 0.7–2 mm., unequal elliptic. Corolla with a very short tube; lobes 5–12 x 3.5–6 mm., obovate-ellipric, obtuse at the apex, with a pair of fimbriate nectaries within, near the base. Stamens inserted at the sinuses; filaments 4–6 mm. long; anthers 1–1.3 mm. long, narrowly ellipsoid. Ovary 4–5 x 2–2.5 mm., narrowly ellipsoid, narrowed into a short stout style; stigma bilobed, papillate. Capsule 7–10 x 3–3.5 mm., narrowly-ellipsoid. Seeds 0.3–0.4 mm. long; testa faveolate.