Planodes virginicum (Linnaeus) Greene, Leafl. Bot. Observ. Crit. 2: 221. 1912; Cardamine virginica Linnaeus, Sp. Pl. 2: 656. 1753; Arabis virginica (Linnaeus) Poiret, Encycl. Suppl. 1: 413. 1810; Sibara virginica (Linnaeus) Rollins, Rhodora 43: 481. 1941. TYPE: United States, “Habitat in Virginia,” (lectotype designated by Marhold (1996: 128), Clayton 462 (BM 000042604).
Cardamine ludoviciana W. J. Hooker, J. Bot. (Hooker) 1: 191. 1834; Arabis ludoviciana (Hooker) C. A. Meyer, Index Sem. Hort. Petrop. 9: 60. 1843. TYPE: United States, banks of the Mississippi, Thomas Nuttall s.n. (holotype, K or BM).
Herbs, annual, pubescent or glabrous. Stems (0.5–)1–3.5(–5.5) dm, 1 to many from base, erect, ascending, to decumbent, branched or rarely simple above, hirsute or puberulent basally, often glabrous above. Basal leaves and lowermost cauline leaves with petioles (0.3–)0.8–21.5(–2) cm; leaf blade oblong to oblanceolate in outline, (1–)1.5–7(–10) x 0.4–2(–3) cm, pinnatifid to pinnatisect, pubescent or rarely subglabrous; lateral lobes (4–)6–12(–15) per side, ovate, oblong, to linear, often coarsely dentate on proximal margin, entire or minutely dentate on distal one, gradually increasing in size towards leaf apex; terminal lobes same size or larger than lateral ones, entire or laterally 1-toothed; middle and upper cauline leaves with shorter petioles, smaller, with narrower and entire lobes. Racemes lax in fruit; fruiting pedicels divaricate-ascending, (1.5–)2.5–6(–8) mm, glabrous, straight, slender. Sepals oblong, 1–2 x 0.5–0.8 mm; petals white, oblanceolate, 2–3 x 0.5–1 mm; filaments 1.5–2 mm; anthers ovate, 0.3–0.4 mm. Fruit linear, (1–)1.5–2.5(–3.2) cm x 1–1.5 mm, slightly torulose, latiseptate, straight, divaricate-ascending; valves glabrous; style 0.2–0.7 mm. Seeds brown, orbicular or nearly so, 1–1.2 x 0.9–1 mm; wing 0.1–0.15 mm. 2n = 16.
Habitat: fields, floodplains, waste places, lawns, railroad tracks and embankments, roadsides, cultivated ground, stream sides, open woods.
Elevation: 0–500 m.
Distribution: Mexico (Baja California), United States (Alabama, Arkansas, California, Florida, Georgia, Illinois, Indiana, Iowa, Kansa, Kentucky, Louisiana, Mississippi, Missouri, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia).