Stems simple or branched, to 25(–42) cm; branches 1–7 pairs, from middle or distal cauline nodes; cauline internode lengths 2–3 times subtending leaves. Leaves: blade oval to oblong or ovate, 2–10 mm, margins serrate, teeth 1–5(or 6) pairs, apices subacute, sometimes aristate. Inflorescences sparsely spicate, not 4-angled, beginning at node (7–)10–12; bracts green, sometimes purplish adaxially, broader than leaves, oblong to ovate, length not more than 2 times width, 5–8 mm, not glossy, margins ciliate, surfaces glabrous or hirsute and hairs eglandular, teeth 4–6 pairs, longer than wide, apices acute to long-aristate. Flowers: corolla white to lilac, 5–7.5(–8.5) mm, lips +/- equal. Capsules narrowly oblong, 4–5.5 mm, apex truncate to retuse. 2n = 44 (England).
Phenology: Flowering early summer–fall.
Habitat: Dry or moist, grassy, gravelly, or sandy places, pastures, roadsides, cliff ledges, wood margins, coastal or inland.
Elevation: 0–1300 m.
Introduced; St. Pierre and Miquelon, Alta., B.C., N.B., N.S., Ont., P.E.I., Que., Alaska, Maine, Mich., Minn., N.H., Oreg., Vt., Wash., n, c Europe.