Flora of North America species comparison

erect to ascending, branched from base;

branches arcuate or, occasionally, almost prostrate.

erect, rarely ascending, branched above base (occasionally with slender branches near base);

branches straight or slightly arcuate.

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.

alternate;

blade filiform to narrowly linear, 1–2 mm wide, less than 1 mm wide in herbarium specimens, usually not fleshy, sometimes semi-amplexicaul at base, apex with soft bristle (rarely subspinescent).

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.

not interrupted, dense, 1-flowered (rarely 2–3-flowered), often also in axils of proximal leaves and branches, lower ones tightly enclosed in bracts and bracteoles, forming gall-like caducous balls at maturity;

bracts alternate, strongly imbricate and appressed at maturity, base not distinctly swollen, apex acuminate into subulate spine.

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.

bracteoles becoming connate basally and adnate to perianth segments;

perianth segments wingless or with narrow, erose wing at maturity, apex acute, weak and flaccid, glabrous; fruiting perianth ca. 2–5 mm diam. 2n = 18.