Flora of North America species comparison

terete, often with 8–12 blunt ridges when dry, 8–80 cm × 0.3–1.4 mm, firm to soft, internally spongy.

terete or cross section elliptic (or rectangular), usually with to 8 blunt ridges when dry, 10–50 cm × 0.2–0.7(–1) mm, soft to firm, spongy.

distal leaf sheaths persistent, not splitting, proximally red (to stramineous), distally green to stramineous, usually inflated, often callose, membranous to papery, apex often red-brown, broadly obtuse to subacute, tooth sometimes present, to 0.1 mm.

distal leaf sheaths persistent, not splitting, mostly proximally dark red, distally red to brown or green, thinly papery to thickly membranous, apex usually redbrown, subtruncate to obtuse or subacute, callose, tooth often present on most or all culms, to 1 mm.

ovoid to lanceoloid or nearly cylindric, 3–18 × 2–3(–4) mm, apex acute (to obtuse);

proximal scale amplexicaulous, entire;

subproximal scale with flower;

floral scales often spreading in fruit, 15–50, 4–5 per mm of rachilla, medium brown to sometimes red-brown, midrib regions mostly stramineous to green, in proximal part of spikelet ovate, apex rounded, in distal part lanceolate, apex entire, acute, 2–3.5 × 1.5–1.7 mm, mostly carinate.

narrowly lanceoloid (to narrowly cylindric), 3–20 × 1.5–2.5 mm, apex acute;

proximal scale amplexicaulous, entire;

subproximal scale empty or with flower;

floral scales appressed or spreading in fruit, 15–40, 3–4 per mm of rachilla, orange brown, midrib regions often greenish, ovate, 2–3 × 1 mm, apex entire, rounded to obtuse in proximal part of spikelet, acute in distal part, carinate, at least in distal part of spikelet.

perianth bristles 4 or absent, light brown to stramineous, stout, usually equal, equaling achene to slightly exceeding tubercle;

stamens 3;

anthers dark yellow to stramineous, 1–1.8 mm, apiculate;

styles 2-fid.

perianth bristles 3–7, rarely apparently absent, stramineous to whitish, slender to stout, often unequal, rudimentary to slightly exceeding tubercle;

stamens 3;

anthers yellow to stramineous, 1.1–2 mm;

styles 3-fid, 0.3–0.4 × 0.2–0.3 mm.

not persistent, dark yellow, stramineous, or dark brown, obovoid to obpyriform, biconvex, angles obscure, 0.9–1.6 × 0.7–1.2 mm, apex rounded, neck absent to long, smooth at 30X, or sometimes finely rugulose at 10–30X with 20 or more horizontal ridges in a vertical series.

falling with scales, yellow-brown or dark brown, ellipsoid or obovoid to obpyriform, compressed-trigonous, angles evident to obscure, rarely prominent, 0.8–1.4 × 0.5–0.7 mm, neck absent to long, smooth or sometimes minutely cancellate at 20–30X.

brown to whitish, pyramidal, much higher than wide to, lower than wide, 0.35–0.65 × 0.2–0.6 mm.

whitish, pyramidal, often higher than wide, 0.3–0.4 × 0.25–0.35 mm.

= 16, 18, 19, 20.

= 10.