Plants glabrous, glaucous. Stems 20–100 cm. Leaf blades 2–10 cm, base cuneate to cordate. Cymes open, 16–50(–100)-flowered. Pedicels (5–)10–30(–55) mm. Flowers: calyx 9–17 mm, with 5 prominent, usually green, winged angles or ridges, each ridge with strong, cordlike marginal vein; petals with claw 8–14 mm, blade 3–8 mm. Capsules included in calyx tube. Seeds 2–2.5 mm wide. 2n = 30.
Phenology: Flowering spring–summer.
Habitat: Fields, waste places
Elevation: 0-2400 m
Alta., B.C., Man., N.B., N.S., Ont., Que., Sask., Yukon, Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Eurasia, widely naturalized elsewhere.
If the genus Vaccaria is treated as monotypic, V. hispanica then includes four subspecies, and our material is subsp. hispanica. Vaccaria hispanica still occasionally is included in Saponaria (e.g., F. Swink and G. S. Wilhelm 1994). Once a common weed of grain fields (like Agrostemma githago), it is now increasingly rare or has been extirpated in many localities; the distribution stated above may be the historical maximum, rather than current, North American distribution. The saponin-containing seeds of this species are poisonous upon ingestion.