Flora of North America species comparison

terete, often with 8–12 blunt ridges when dry, 20–55 cm × 0.3–1.3 mm, soft to hard.

markedly arched, not spirally twisted, not contracted near spikelet, when dry usually with several blunt to acute ridges and sulcate, subterete to slightly compressed, to 2 times as wide as thick, 5–15 cm × 0.5–1 mm, firm to hard;

culm tufts not proximally bulbous.

distal leaf sheaths persistent, rarely splitting, proximally red to stramineous, distally green to reddish, papery, apex often dark reddish, subtruncate to obtuse, not callose, tooth present on some or all culms of plant, to 0.5 mm.

distal leaf sheaths brown to reddish proximally, stramineous to reddish distally, apex sometimes reddish, membranous to papery.

cylindric to ovoid, 5–20 × 2–3 mm, apex rounded to subacute;

proximal scale amplexicaulous, apex entire;

subproximal scale empty;

floral scales appressed in fruit, 20–200+, 10 per mm of rachilla, dark brown, midrib regions often stramineous or greenish, oblong, 1.7–2.5 × 1 mm, apex entire, broadly rounded, usually recurved, mostly carinate.

3–6 × 2–4 mm;

proximal scale empty, 2.5–4 mm, 1/2 or more as long as spikelet;

floral scales 4–9 per spikelet, 3.5–5 × 2 mm.

perianth bristles absent;

stamens 3;

anthers dark yellow, 1–1.5 mm;

styles 3-fid.

perianth bristles 4–7, very unequal, some shorter than 1/2 of achene, stout and smooth, others equaling or exceeding tubercle, very slender and densely spinulose;

anthers 1–1.5 mm.

falling with scales, medium to dark brown, obovoid to obpyriform, with short neck, thickly trigonous, angles prominent (keeled), 0.7–0.9 × 0.4–0.6 mm, obscurely to clearly rugulose at 10–20X with more than 20 horizontal ridges in vertical series and/or minutely cancellate at 20–30X.

medium brown, equilaterally trigonous to compressed trigonous or some biconvex, 1.5–2.1 × 0.9–1.2 mm, beak 0.2–0.3 × 0.3–0.4 mm.

brown, rudimentary, mostly apiculate, sometimes pyramidal, 0.05–0.15 × 0.15–0.2 mm.

0.25–0.5 × 0.15–0.2 mm.