Flora of North America species comparison

terete, often with 8–12 blunt ridges when dry, 20–55 cm × 0.3–1.3 mm, soft to hard.

obscurely trigonous to terete;

spikelet-bearing culms 16–80 cm × 0.5–1.5 mm; when submersed plants often forming numerous, filiform flaccid culms without spikelets, sometimes with whorls of slender branches, 0.1–0.3 mm wide, soft;

sometimes septate-nodulose when aquatic, internally spongy, transverse septa incomplete.

distal leaf sheaths persistent, rarely splitting, proximally red to stramineous, distally green to reddish, papery, apex often dark reddish, subtruncate to obtuse, not callose, tooth present on some or all culms of plant, to 0.5 mm.

distal leaf sheaths persistent or decaying, membranous, apex acute, often prolonged into translucent portion to 1 mm.

cylindric to ovoid, 5–20 × 2–3 mm, apex rounded to subacute;

proximal scale amplexicaulous, apex entire;

subproximal scale empty;

floral scales appressed in fruit, 20–200+, 10 per mm of rachilla, dark brown, midrib regions often stramineous or greenish, oblong, 1.7–2.5 × 1 mm, apex entire, broadly rounded, usually recurved, mostly carinate.

not proliferous, (6–)9–24 × 1.4–2.2 mm;

rachilla joints bearing prominent winglike remnants of floral scales;

proximal scale with a flower, amplexicaulous, 2.5–4.1 mm;

floral scales 7–26, 1–2 per mm of rachilla, green to stramineous or pale brown, often minutely dotted reddish, usually with conspicuous dark brown to blackish submarginal band, narrowly ovate, 3.5–4.5 × 2 mm, thickly papery, membranous toward margins.

perianth bristles absent;

stamens 3;

anthers dark yellow, 1–1.5 mm;

styles 3-fid.

perianth bristles 6–7, whitish to stramineous or pale reddish brown, proximally slightly flattened, unequal, exceeding or rarely shorter than achene, 0.7–1.9 mm, retrorsely spinulose;

anthers yellow to reddish, 1.7–1.9 mm;

styles 3-fid.

falling with scales, medium to dark brown, obovoid to obpyriform, with short neck, thickly trigonous, angles prominent (keeled), 0.7–0.9 × 0.4–0.6 mm, obscurely to clearly rugulose at 10–20X with more than 20 horizontal ridges in vertical series and/or minutely cancellate at 20–30X.

whitish, stramineous, or pale green, obovoid to obpyriform, compressed trigonous with adaxial face broadest, or biconvex, 0.65–1.4 × 0.5–0.8 mm, clearly sculptured at 10–15X, each face with 10–13 rows of rectangular, transversely elongated cells, apex constricted to short neck 0.2–0.25(–0.3) mm wide, wider at tubercle base.

brown, rudimentary, mostly apiculate, sometimes pyramidal, 0.05–0.15 × 0.15–0.2 mm.

dark brown, pyramidal, 0.2–0.5 × 0.2–0.4 mm.