Annual dwarf herb, 3–15 cm tall, with appressed pubescent and setose, tubercle-based hairs. Leaves are opposite, sessile, and linear, 5–25 mm long and 1–2 mm wide. Flowers are white, sessile, solitary, and axillary. Calyx is composed of five linear-partite lobes, 3–4 mm long. Corolla is white, tubular-campanulate, 2–3 mm long. Flowers have five included stamens borne above the base of the tube, with anthers as long as the filaments. Fruits are ovoid, keeled nutlets, about 1.5 mm long, with a granular-tuberculate surface.