Fl. S.E. U.S., 1065, 1338. 1903.
Stems spreading, prostrate, or ascending, 10–60 cm, glandular. Leaves glandular; blade 10–25 × 6–12 mm, 4–8 times bracts, margins sharply serrate. Pedicels ascending, 7–25 mm. Flowers: calyx lobes equal; corolla lemon yellow with reddish veins in throat, abaxial lip prominent, adaxial lobes connate nearly to apices; stamens medially adnate to corolla. Capsules 4–5 mm. Seeds 60–80, brown, radial walls of reticulum mamillate. 2n = 22, 44.
Phenology: Flowering May–Oct.
Habitat: Wetlands, edges of streams, springs and seeps, deserts in upland washes and canyons with moisture.
Elevation: 90–1600 m.
Ala., Ariz., Fla., Ga., La., Miss., N.Mex., Tex., Mexico, Central America, introduced in Asia (India, Sri Lanka), Africa (Cameroon, Sierra Leone), Australia.