Flora of North America species comparison

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

2–4 × 1–2 mm, sometimes absent in deeper water;

proximal scale 1/2 or more of spikelet length;

floral scales 6–10 per spikelet, 1.4–2.7 mm, commonly entirely stramineous, apex rounded to subacute.

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, stramineous, fairly stout to slender, usually equaling achene to slightly exceeding tubercle, sometimes unequal and some 1/2 of achene, very rarely rudimentary, minutely retrorsely spinulose;

anthers 0.7–1.2 mm.

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

stramineous, sometimes pale brown, obovoid to obpyriform, thickly trigonous, angles distinct, faces concave to plane, rarely convex, 0.9–1.2 × 0.55–0.75 mm, apex tapered, smooth or faintly rough at 30X.

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

beak 0.3–0.6 mm.

terminating rhizomes usually markedly J- or horseshoe-shaped, body (apart from apical bud) oblong, 2–2.5(–5) × 0.5–1 mm;

tubers among culm bases straight, narrowly fusiform, 4–5 mm.

0.1–0.2 × 0.15 mm.

0.25–0.6 × 0.3–0.55 mm.

1.8 –3 mm.

= 10 (Europe).