Sp. Pl. 1: 222. 1753.
Herbs, 5–50 cm, papillose to hispid or, occasionally, glabrous. Stems erect to ascending, branched from base; branches arcuate or, occasionally, almost prostrate. Leaves alternate; blade linear, mostly 1–2 mm wide in herbarium specimens, fleshy, usually not swollen at base, apex ± acuminate into rather firm, 1–1.5(–2.2) mm spine. Inflorescences interrupted at maturity, usually 1-flower per axil of bract; bracts alternate, not imbricate at maturity, reflexed, not distinctly swollen at base, apex narrowing into subulate spine. Flowers: bracteoles free or becoming connate and adnate to perianth base; perianth segments with comparatively narrow wing or in lower flowers occasionally wingless (in S. kali subsp. pontica sometimes prominently winged), with weak or firm, acute apex, glabrous; fruiting perianth 4–6(–8) mm diam. 2n = 36.
N.B., N.S., Nfld. and Labr. (Nfld.), P.E.I., Que., Ala., Calif., Conn., D.C., Del., Fla., Ga., La., Maine, Mass., Md., Miss., N.C., N.H., N.J., N.Y., Oreg., Pa., R.I., S.C., Tex., Va., coastal areas of Europe, n Africa, sw Asia, introduced and naturalized in other coastal regions.
Subspecies ca. 2 (2 in the flora).