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.

subterete to slightly compressed, less than 2 times wider than thick, with 4–7 blunt ridges when dry, 27–56 cm × 0.2–0.5(–0.7) mm, firm to hard, spongy.

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

distal leaf sheaths persistent, not splitting, proximally red, distally green to stramineous, often inflated, thinly papery to membranous, sometimes translucent, apex broadly obtuse to subtruncate, often callose, tooth absent.

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.

ovoid, 3–10 × 2–3 mm, apex acute;

proximal scale amplexicaulous, apex 2-fid;

subproximal scale with a flower;

floral scales spreading in fruit, 20–50, 7 per mm of rachilla, medium brown, midrib region often narrowly stramineous, carinate, lanceolate-attenuate, 2–2.8 × 1 mm, apex 2-fid.

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.

perianth bristles 3 or absent, stramineous to pale brown, rudimentary to 1/2 achene length, obscurely retrorsely spinulose;

stamens 3;

anthers orange-brown, 0.7–1.3 mm;

styles 3-fid.

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.

falling with scales, medium or dark brown, obpyriform, nearly equilaterally obscurely trigonous or cross section nearly circular, 0.7–1 × 0.5–0.65 mm, neck distinct or rarely absent, obscurely rugulose at 10–30X, 30 or more low, blunt horizontal ridges in vertical series.

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

brown, depressed-pyramidal, often rudimentary, 0.1–0.15 × 0.2 mm.