Flora of North America species comparison

subterete, often with to 6 prominent ridges when dry, sulcate, 10–30 cm × 0.3–0.5 mm, firm to rigid, spongy.

subterete to sometimes compressed, to (2–)3 times as wide as thick, often with (4–)5–10 ridges or angles, 5–90 cm × 0.3–0.8 mm, firm to soft, spongy.

distal leaf sheaths persistent, not splitting, proximally brown, red, or stramineous, distally stramineous, green or reddish, papery, apex sometimes reddish, obtuse, rarely callose, tooth absent.

distal leaf sheaths persistent, not splitting, proximally dark red, distally green to stramineous or red, thinly papery to membranous, apex usually red-brown, obtuse to subacute, often callose, tooth to 0.5 mm usually present on some culms.

ovoid, 3–8 × 2–3 mm, apex acute to obtuse;

proximal scale amplexicaulous, entire;

subproximal scale with flower;

floral scales spreading in fruit, 8–30, 4–5 per mm of rachilla, dark brown to blackish, midrib regions often stramineous or greenish, ovate to lanceolate, 2–3 × 1.5 mm, apex entire, acute, often carinate in distal part of spikelet.

ovoid, 3–8 × 2–3(–4) mm, apex obtuse (to acute);

proximal scales amplexicaulous, apex entire;

subproximal scale with a flower;

floral scales spreading in fruit, 10–30, 5–7 per mm of rachilla, medium to very dark brown, midrib region often paler, ovate, 1.7–3 × 1–1.5 mm, apex rounded to obtuse (or acute), entire or shallowly notched (emarginate) or sometimes cut to 0.5(–0.7) mm deep, apical colorless hyaline part at least as wide as long, 0.2–0.7 mm, carinate in distal part of spikelet.

perianth bristles 3–6, whitish to stramineous, stout to slender, often unequal, from rudimentary to 1/2 of achene length;

stamens 3;

anthers dark yellow to brown, 0.9–1.4 mm;

styles 3-fid.

perianth bristles absent or rarely 1–3, pale brown, to 1/2 of achene length, sparsely retrorsely spinulose;

stamens 3;

anthers orange-brown, 0.8–1.7 mm;

styles 3-fid or some 2-fid.

falling with scales, stramineous, rarely dark brown, ovoid to obpyriform, slightly to greatly compressed-trigonous, rarely thickly lenticular, angles prominent or abaxial angle obscure, 0.9–1.2 × 0.65–0.8 mm, apex narrowly to broadly truncate, neck short, often compressed more than body, at 20–30X finely rugulose with more than 20 horizontal ridges in a vertical series or reticulate or cancellate.

persistent after scales fall, usually lemon yellow or dark yellow, orange, or medium brown, rarely greenish, obpyriform, nearly equilaterally to compressed-trigonous, often some biconvex, angles evident to prominent, 0.7–1.2 × 0.6–0.9 mm, neck short or absent, finely to coarsely rugulose at 10X, 12–20 horizontal ridges in vertical series, usually finely cancellate at 10–20X.

whitish to brown, pyramidal, lower than wide, often 3-lobed as viewed from the top, 0.1–0.3 × 0.4–0.65 mm.

brown to whitish, greatly depressed, apiculate, sometimes pyramidal, 0.1–0.25 × 0.25–0.45 mm.

= 38.