Flora of North America species comparison

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

branches straight or slightly arcuate.

erect, rarely ascending or prostrate, profusely branched from or near base (rarely simple in underdeveloped specimens);

branches straight or arcuate.

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).

alternate;

blade filiform to narrowly linear, usually less than 1 mm wide, occasionally to 2 mm wide in herbarium specimens, fleshy or not, not swollen at base, apex subspinose or spinescent.

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.

distinctly interrupted at maturity, 1-flowered (rarely 2–3-flowered with lateral flowers mostly abortive);

bracts alternate, not imbricate, strongly reflexed at maturity, base not distinctly swollen, narrowing into spinose apex.

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.

bracteoles spreading or reflexed, distinct or connate near base, spinescent;

perianth segments prominently winged (two wings usually reduced to small, almost subulate winglike appendages), apex long-acuminate or long-subulate and spinose, forming slender columnar beak distal to wings at maturity, glabrous; fruiting perianth 7–12 mm diam. 2n = 36.