Herbs perennial; most parts short strigose. Roots containing little purple dye when young. Stems usually single, erect, to 1 m tall, frequently much branched at apex. Leaves sessile, lanceolate to ovate-lanceolate, 3-8 × 0.5-1.5 cm, base cuneate to attenuate, apex short acuminate; veins prominent abaxially, more densely strigose along veins. Inflorescences on upper stems and branches, to 15 cm in fruit; bracts similar to leaves but smaller. Calyx lobes linear, ca. 5-7 mm in fruit. Corolla white or pale yellow, 4-6 mm; tube ca. 2 × as long as limb; throat with 5 trapeziform, densely short pubescent appendages ca. 0.4 mm; lobes of limb erect, oblong-ovate, ca. 1.5 mm, margin undulate. Stamens inserted at middle of corolla tube; filaments ca. 0.4 mm; anthers ca. 1.2 mm. Stigma capitate. Nutlets white or yellowish brown, ovoid, ca. 3 mm, smooth, shiny, concave adaxially with center line forming a longitudinal groove. Fl. and fr. Jun-Aug. 2n = 28, 56.
"Erect, usually much branched perennial to 1 m, the principal internodes usually less than 2 cm; lvs subsessile, lanceolate to oblong or oblanceolate, 6–15(–20) mm wide, gradually acute, with 2 or 3 conspicuous lateral veins on each side; fls solitary in the crowded upper axils, 3–15 mm apart at maturity, white or nearly so, 4–5 mm; cal-lobes nearly as long as the cor; nutlets ovoid, 3–3.5 mm, white to pale brown, shining, smooth or sparsely pitted; 2n=28. Native of Eurasia, intr. as a weed of waste places from Que. to Minn., s. to N.J. and Ill. May–Aug."