in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 10: 468. 1846.
Perennials. Stems decumbent or ascending, 5–50 cm, glabrous. Leaves: petiole 2–6(–10) mm; blade ovate to lanceolate, widest proximal to middle, (5–)30–50(–100) × (3–)7–20(–30) mm, 2–4 times as long as wide, base truncate, rounded or almost cordate, abruptly turning into petioles, margins entire or serrate, apex obtuse-orbicular or acute, surfaces glabrous. Racemes 1–8, axillary, 30–100 mm, (3–)10–30-flowered, axis glabrous; bracts lanceolate, 3–6 mm. Pedicels patent, 3–10(–12) mm, equal to ± longer than subtending bract, glabrous. Flowers: calyx lobes 2–5(–6) mm, apex acute, glabrous; corolla pink or sky blue, 4–10 mm diam.; stamens 2–4 mm; style (1.7–)2.5–3.5(–4) mm. Capsules slightly compressed in cross section, globular, 2–4 × 3–5 mm, apex not or ± emarginate, glabrous. Seeds 20–30, brownish, ellipsoid to ovoid, indistinct-compressed or planoconvex, 0.5–0.7 × 0.3–0.6 mm, thickness varies due to compression in capsule, indistinctly wrinkled or ± rugose. 2n = 36.
Phenology: Flowering May–Aug.
Habitat: Slowly flowing waters, banks, sand bars, gravel flood plains, moist soils, springs, ditches, swamps, marshes.
Elevation: 0–3600 m.
Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon, Alaska, Ariz., Ark., Calif., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., 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., Wyo., Mexico, Asia (Japan, Russia).
Although difficult to separate, Veronica beccabunga and V. americana are maintained as species here. Evidence suggesting separate species status is different ploidy level (the tetraploid level is rare in V. beccabunga) and the occurrence of V. americana in more natural habitats.