Sp. Pl. 1: 178. 1753.
Annuals or biennials. Stems 60–150 cm, glabrous or glabrate. Leaves: surfaces glabrous or glabrate; basal and proximal cauline with petiole 1–2 mm; blade obovate to oblanceolate, oblong, or oblong-lanceolate, 4–12(–20) × 1.5–5 cm, base subrounded to broadly cuneate; cauline subclasping, gradually smaller distally, base not decurrent, margins coarsely and regularly crenate-dentate to dentate or pinnately dentate-lobed, apex of distal cauline and floral bracts acute. Inflorescences unbranched, rarely branched from proximal nodes, narrowly cylindric, flowers remote, solitary in axils at least distally; rachis stipitate-glandular, without other vestiture; bracts ovate to lanceolate-ovate, 7–10(–15) mm, base decurrent, apex acute to short-acuminate, stipitate-glandular. Pedicels free or adnate to rachis at base, 5–11(–15) mm; bracteoles 0. Flowers: calyx 5–7 mm, stipitate-glandular, lobes linear-lanceolate to narrowly oblong; corolla purple in bud, becoming yellow, yellow-orange, yellow with purple center, white, cream with red-tinged tips, or pink, 25–35 mm diam., pellucid glands absent or relatively few; proximal filaments hairy, hairs purple, distal pair villous, hairs white and purple or violet; stigma spatulate, base decurrent. Capsules subglobular, 5–8 mm, sparsely stipitate-glandular apically. 2n = 18, 30, 32.
Phenology: Flowering May–Jul(–Oct).
Habitat: Stream banks, lake edges, ditches, dry hills, railroad rights-of-way, orchards, prairies, open oak woods, rocky meadows, roadsides, fields, disturbed sites.
Elevation: 0–1300 m.
Introduced; B.C., N.B., Ont., Que., Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Europe, Asia, introduced also in Pacific Islands (Hawaii, New Zealand), Australia.
Verbascum ×pterocaulon Franchet is a hybrid between V. blattaria and V. thapsus.