Fl. Belg., 35. 1827.
Plants 4–120 cm. Leaves: petiole 2–6 mm; blade: proximal 15–35 × 10–30 mm, base truncate or rounded to cuneate, distal 4–25 × 2–14 mm, base hastate to sagittate, villous with scattered glandular-hairs. Pedicels 10–22 mm. Flowers: sepal lobes lanceolate, 3–6 × 1–2 mm, not accrescent, apex acuminate, villous; corolla-tube 1–2 mm, palate yellow, inflated, hairy, spurs 5–6 mm, abaxial lobes yellow to violet, adaxial blue to violet, 2–3 mm; abaxial filaments 1.5–2 mm, adaxial 1–1.5 mm; style included, 1.3–1.5 mm; stigma straight. Capsules ovoid-globular, 3–5 mm. Seeds 1–1.5 mm, cristate-tuberculate. 2n = 36.
Phenology: Flowering May–Oct(–Dec).
Habitat: Gravelly or sandy disturbed sites, roadsides, stream banks, gravel bars, glades.
Elevation: 0–900 m.
Introduced; B.C., Ont., Ala., Ark., Calif., Conn., Del., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Mich., Mo., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Va., Wash., W.Va., Wis., Eurasia, n Africa, also in Mexico, Central America, South America, Atlantic Islands, Australia
Kickxia elatine differs from K. spuria in leaf and calyx characters. Two subspecies of K. elatine have been described [subsp. elatine and subsp. crinita (Mabille) W. Greuter]; they are poorly defined (D. A. Sutton 1988; M. Ghebrehiwet 2001) and differentiated on the basis of indument density.