Flora of North America species comparison

roundly trigonous to terete, 30–80 cm × 1–1.6 mm, glabrous.

solitary or not, trigonous or round, glabrous or scabridulous with extrorse or antrorse (rarely retrorse) prickles.

1–6, 10–40 cm, glabrous or essentially so.

usually basal;

ligules absent;

blades keeled abaxially, flat, V-, or inversely W-shaped in cross section.

heads ovoid to pyramidal, 9–15 mm diam.;

rays 0 or 3–6, 0.5–4 cm, glabrous;

bracts 3–4, longest erect, appearing as continuation of culm, others horizontal to ascending, 4–17 cm × 1.5–4 mm.

terminal, rarely pseudolateral, 1st order subumbellate to capitate, 2d order with spicate or digitately arranged spikelets, rarely a solitary spikelet;

spikelets 1–150; 1st order rays unequal (rarely equal) in length, produced singly from the axils of inflorescence bracts;

involucral bracts 1–22, spirally arranged at culm apex, spreading to erect, leaflike.

25–60, reddish with contrasting yellowish or greenish edges, oblong-lanceoloid, strongly compressed, 5–6(–15) × 1.5–2.5 mm;

floral scales 10–22, laterally reddish, medially yellowish green, 2-keeled, laterally strongly 1-ribbed on each side, proximally grooved, ovate-elliptic, 1.4–2.2 × 0.8–1.5 mm, apex acute, apically scabridulous (sometimes glabrous).

scales to 76, distichous, each subtending flower, cylindric to compressed, borne spicately or digitately at ends of rays (occasionally proliferous).

stamen 1;

anthers 0.6–1 mm;

styles 0.3–0.5 mm;

stigmas 0.3–0.6 mm.

bisexual [rarely unisexual], in axils of distichous floral scales, bases often decurrent onto rachilla as ± hyaline wings;

perianth absent;

stamens 1–3;

styles linear, 2–3-fid, base deciduous or persistent;

stigmas 2–3.

reddish brown, stipitate, ovoid-ellipsoid, 0.8–0.9 × 0.3–0.4 mm, stipe 0.1–0.2 mm, apex acute to acuminate, surfaces reticulate or subtly rugulose.

biconvex, flattened, or trigonous.