Sepals 2-3 mm, to 4 mm in fruit. Capsules ovoid to ovoid-conic, broader at base. Seeds 0.5-0.6 mm. 2n = 40, 44- (both Europe).

Flowering spring-summer. Roadsides, open, sandy or rocky, disturbed sites; 0-1800 m; introduced; St. Pierre and Miquelon; Alta., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask.; Ala., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., 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.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Eurasia; n Africa; introduced in Australia.

In very sandy soil along roadsides and railroads, in fallow fields, and rarely on bare spots on bluffs of streams. Naturalized in Indiana; I believe it could be found in railroad ballast in every county of the state.