Description

Key Characters:

Growth Form: Annual or short-lived perennial herbs.

Stems: Stems 5–10 dm long, many-branched, sparsely to densely villous, especially when young.

Roots:

Leaves: Leaves simple. Opposite. Blades ovate to elliptic–ovate, 3–6 (–11) cm long, 1.3–3(–5) cm wide. Apex acute. Base cuneate. Upper surfaces puberulent; lower surfaces strigose on veins. Surfaces copiously dotted with sessile oil glands. Margins subentire to remotely crenulate. Petioles 1–2 cm long. Stipules absent.

Flowers: Flowers 6–10 usually small, in verticillasters, these arranged in racemose, unbranched or branched inflorescences, pedicels recurved, bracts minute, caducous. Calyx actinomorphic, bilabiate, 2–5 mm long, ovoid or campanulate, deflexed & enlarging up to 9 mm long in fruit, tube ca. 3 mm long, dotted with oil glands, sparsely short–hirsute, sometimes also very sparsely long–hirsute, densely hirsute within at base, 10-nerved, lower teeth as long as or slightly longer than upper tooth, the teeth narrow and pungent, mouth of fruiting calyx open. Corolla bilabiate, campanulate, white, sometimes tinged pink, 7-10 mm long, glabrous within, upper lip erect, subequally 4-lobed, lower lip slightly longer, curved downward, flattened or concave, entire; nectary disk entire or 2–4-lobed, symmetrical. Stamens 4, in 2 pairs, exserted beyond corolla tube; anther sacs confluent; anthers dithecal, opening by longitudinal slits.

Fruit: Nutlets ellipsoid; 1.5–3.5 mm long; pitted; mucilaginous when wet. Seeds with endosperm absent or scanty and oily.

Ploidy: 2n = 16; 48

Habitat: Naturalized in low elevation; dry disturbed habitats.

Elevation Range: 15–400 m.