Annuals or, rarely, perennials. Stems erect to prostrate, to 8 dm. Cauline leaves: blade broadly ovate to lanceolate, (to 10 cm, smaller distally), margins sinuately lobed or deeply pinnatifid, (distal) often subentire; (lateral lobes 4-8, 5-15 mm). Racemes to 4 dm; rachis straight. Fruiting pedicels 1.5-7 mm. Flowers: sepals 4-5.5 mm, lateral pair not saccate basally; petals usually lavender, rarely white, 8-14 × 3-6 mm, claw distinct. Fruits (often reflexed), hastate, 12-27 × 4-8 mm; proximal segment conical (becoming pedicel-like when aborted, with 2 opposite, lateral horns distally); terminal segment usually 4-angled, mitriform or conic, (margins scarious basally), apex acute or blunt, (usually compressed). Seeds: cotyledons accumbent to, sometimes, incumbent or contorted. 2n = 18.

Flowering late spring-fall(-winter if mild). Sandy beaches; ca. 0 m; introduced; B.C.; Calif., Md., Oreg., Wash.; Europe; introduced also in nw Mexico.

Subspecies maritima is naturalized in Pacific North America (M. G. Barbour and J. E. Rodman 1970); it is also reported on the eastern shores of Chesapeake Bay, Maryland.