Flora of North America species comparison

50–150 cm × 4–8 mm.

100–200 cm × 5–15 mm.

sheaths reaching beyond middle of culm, fronts usually convex, papery at mouth, veins reaching margin, or occasionally membranous with veins diverging proximal to apex leaving triangular, veinless area;

widest blade 4–12 mm wide.

sheaths reaching to middle of culm or higher, fronts convex (to concave) and papery at mouth, veins reaching apex, very rarely diverging leaving triangular, veinless, membranous area;

widest blade 7–22 mm wide.

simply branched with 1 or not more than 1/2 of spikelets solitary or in clusters of 2(–3) on 1–7 rays, rays not exceeding 7 cm;

involucral bracts that surpass inflorescence 2–4, widest bract 2–7 mm wide.

subumbellate, with all or most spikelets solitary or in clusters of 2–3(–8) on 4–12 rays, rays not exceeding 10 cm;

involucral bracts that surpass inflorescences 3–6, widest bract 4–15 mm wide.

(1–)5–25, broadly ovoid to rarely lanceoloid, 10–30 × 6–10 mm, base usually truncate;

scales usually tightly imbricate, medium to dark orange-brown, lineolate-spotted at 15X, usually 6–9 × 3–4 mm, papery and nearly opaque, rarely membranous, apex 2-fid, 1 mm deep, awn very stout, 2–3 × 0.5 mm at base.

10–40, ovoid to lanceoloid, 10–25 × 6–10 mm, base cuneate to rounded;

scales often loosely imbricate, orange-brown to stramineous, usually obscurely lineolate-spotted, 7–10 × 3–4 mm, membranous and translucent, apex 2-fid 0.5–1 mm deep, awns fairly stout, 2–3 × 0.5 mm wide at base.

perianth bristles not persistent on shed achene or 1–2 weakly attached to shed achene, dark red-brown, 1/2 achene length;

anthers brownish orange, 1.5–2.5 mm;

styles (2–)3-fid.

perianth bristles tightly attached to shed achene, pale brown, very stout, equaling achene;

anthers yellow, 4 mm;

styles 3-fid.

dark to medium brown, obovoid, compressed-trigonous with broadly rounded abaxial angle or sometimes biconvex, 2.7–3.5 × 1.8–2.8 mm, apex truncate to broadly rounded, beak 0.1–0.3 mm, surface glossy, exocarp cells evident at 10–20X; in achene cross section exocarp 2 times thicker than mesocarp and its cells greatly enlarged, 3 times or more deeper than wide;

achene specific gravity much less than water.

grayish or dark brown, often in patches, obovoid to obpyriform, all nearly equilaterally markedly trigonous to slightly compressed, angles equally rounded, 3.8–5.5 × 2–2.9 mm, apex rounded, beak 0.2–0.8 mm, surface rather dull, exocarp cells usually not evident at 20X; in cross section exocarp much thinner than mesocarp and its cells very small, isodiametric;

achene specific gravity greater than water.

= 94.