Flora of North America species comparison

terete, 45–100 cm × (3.2–)5–9.4 mm, soft to firm, sometimes septate-nodulose proximally, not distally, internally hollow with complete transverse septa, closer together near the spikelet, evident externally;

plants never forming filiform, flaccid culms.

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

distal leaf sheaths persistent, membranous to thinly papery, apex acute to acuminate.

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.

not proliferous, (20–)40–62 × 4–7 mm;

rachilla joints bearing prominent wing-like remnants of floral scales;

proximal scale empty, amplexicaulous, (3–)3.5–5 mm;

floral scales 115–220, 1–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, midrib region sometimes greenish, obovate to broadly oblong, (4–)4.5–5 × 2.8–4 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to subacute.

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.

perianth bristles 6–8, stramineous, stout, flattened, subequal, exceeding achene, to 2.9 mm, coarsely spinulose;

anthers stramineous to reddish, 2.5–5 mm;

styles 2-fid or 3-fid.

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.

stramineous to golden-yellow or reddish brown or gray, obovoid to obpyriform, biconvex or nearly plano-convex, often with abaxial longitudinal ridge, 1.4–1.8(–2) × 1.1–1.4 mm, markedly sculptured at 10–15X, each face with 23–37 rows of transversely elongated cells, the longitudinal walls separating the cells often prominent, apex with short neck 0.7–0.8 mm wide.

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.

dark brown, lamelliform, slightly higher than wide, 0.7–1.1 × 0.5–0.7 mm.

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

= 16, 18, 19, 20.