Flora of North America species comparison

acutely quadrangular, (30–)45–105 cm × (1–)2–5.4 mm, soft to firm, internally spongy, transverse septa incomplete;

plants never forming filiform, flaccid culms.

erect, markedly spirally twisted, markedly obliquely contracted near spikelet, when dry often with to 6 broad, rounded ridges on each side, greatly compressed, 3–4 times as wide as thick, 20–40 cm × 1.5–2.5 mm, firm;

culm tufts not proximally bulbous.

distal leaf sheaths persistent, membranous, apex narrowly acute to acuminate, sometimes prolonged into a bladelike portion to 8 cm.

distal leaf sheaths stramineous to medium (or dark) brown, papery, apex often dark brown to reddish, broadly obtuse.

not proliferous, (15–)20–76 × 3–5(–6) mm;

rachilla joints bearing obscure winglike remnants of floral scales;

proximal scale empty, amplexicaulous, (1–)2.2–5.4 mm;

floral scales (28–)45–135, 2–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, midrib region sometimes greenish, broadly obovate to ovate, (4–)4.5–6.2 × 2.8–5 mm, subcartilaginous, apex rounded to obtuse.

6–8 × 2–3 mm;

proximal scale empty, 3–4 mm, shorter than to equaling spikelet;

floral scales 8–10 per spikelet, 3.5–5 × 2 mm.

perianth bristles 6–7, whitish to brown, slender, often markedly unequal, shorter than achene or some equalling tubercle, sparsely retrorsely spinulose to smooth;

anthers stramineous to red-brown, 2.3–2.9 mm;

styles 3-fid, sometimes 2-fid.

bristles 0–5, unequal, rudimentary to equaling achene, the shorter stout, smooth or nearly so, the longer slender, densely spinulose.

yellow or pale green to brown or purplish, biconvex, obovoid to obpyriform, 1.8–3 × 1.3–2 mm, almost smooth to markedly sculptured at 10–15X, each face with 19–38 rows of almost linear, transversely elongated cells, which are sometimes isodiametric at achene base, apex often constricted to neck 0.3–0.4 mm wide.

stramineous to medium brown, thickly trigonous, 1.75–2.75 × 1–1.25 mm;

beak 0.3–0.6 mm.

dark brown or whitish, deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy.

0.25–0.6 × 0.3–0.55 mm.

1.8 –3 mm.