Index Seminum (St. Petersburg) 2: 4. 1836.
Stems simple or with few ascending branches, (8–)12–50(–100) cm, densely glandular-hairy. Leaves 6–30 pairs, ascending or divaricate, glandular-hairy; blade oblong-lanceolate, (10–)20–46 x 3–18 mm, margins green, apex acute. Spikelike racemes 3–30 cm; flowers 4–35 pairs, interrupted proximally, dense distally, glandular-hairy; peduncle absent; bracts foliaceous, 15–25 x 3–6 mm, margins crenate-dentate. Pedicels 1 mm, glandular-hairy. Flowers: calyx campanulate, 10–16 mm, tube 8–10 mm, glandular-hairy, lobes +/- equal, narrowly lanceolate, 4–10 x 1.5–2 mm, herbaceous, margins entire, apex acute, glandular-hairy; corolla yellow, 20–25 mm, glandular-hairy externally, throat with 2 inflated lines between lateral and central lobes, abaxial lobes spreading, adaxial projecting; stamens included, pollen sacs yellow, 1–2 mm, glabrous proximally, villous distally around pore, dehiscing longitudinally in distal 3/4–4/5; style 10–20 mm, short-strigose; stigma capitate. Capsules 6–10 x 2–4 mm, long-strigose. Seeds 0.2–0.3 mm, smooth. 2n = 48.
Phenology: Flowering Apr–Sep.
Habitat: Wetland prairies, fields, pastures, beach foreshores, roadsides.
Elevation: 0–1500 m.
Introduced; B.C., Ariz., Ark., Calif., La., Miss., Okla., Oreg., Tex., Wash., Europe, introduced also in s South America, e Asia, n Africa, Atlantic Islands, Pacific Islands (Hawaii, New Zealand), s Australia.