Annual herb, to 70 cm high. Stem slender, branched from the base, ridges smooth or minutely winged. Leaves membranous, ovate or ovate-lanceolate to elliptic-lanceolate, 6–48 mm long, 4–18(–23) mm wide, acute, cuneate at base. Inflorescences dichasial cymes, diffuse, sometimes ± slightly contracted; bracts 4–8.5 x 2–4(5) mm, ovate, acute; pedicels 5–10 mm long, very slender. Flowers usually 4-merous (rarely 5-merous), irregular. Calyx tube 4–7 mm long; lobes unequal, linear-lanceolate, 1–2 mm long, ± 1 mm wide, acuminate. Corolla tube cylindrical, 4–7 mm long; lobes unequal, 2 shorter and 2 longer, 2.2–4 mm long, ± 1–2 mm wide, emarginate. Filaments unequal, 1 longer, always inserted higher up in the corolla tube, ± 0.4–0.8 mm long, 3 shorter, 0.2–0.3 mm long, inserted lower down; anthers up to 0.5 mm long, oblong, 1–2 perhaps sterile. Ovary up to 3.2 mm long; style 1.2–1.8 mm long; stigma 0.3–0.5 mm long, bilobed, lobes unequal, papillose. Capsule oblong to ellipsoid, 3.8–11 mm long, ± 3 mm diameter. Seeds numerous, up to 0.3 mm in diameter, surface reticulate-pitted. Fig. 12 (p. 41).
