Erect annual herb, (6–)25–40 cm high; stems suffused purple, simple or usually branched in upper part, quadrangular, glabrous. Leaves linear to lanceolate, 3–19 mm long, 2–7 mm wide, sessile, apex acute, margins ± serrate, scabrid-ciliate on the margins, 1–3-veined. Flowers terminating each branch, few together or shortly spicate, almost sessile. Bracts lanceolate. Calyx 5 mm long with 5 wide purple longitudinal bands, teeth triangular, acute, scabrid. Corolla 5–7 mm long, lower lip 3-lobed, violet with a whitish spot in middle and two yellow marks in throat, upper lip deep mauve; anthers bluish, pollen white. Capsule oblong, 5 mm long, acute. Seeds suborbicular, grooved down one side.
