Flora of North America species comparison

acutely trigonous;

spikelet-bearing culms 16–70 cm × 0.7–0.9 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.

erect, not spirally twisted, not contracted near spikelet, when dry usually with several blunt to acute ridges and sulcate, subterete to slightly compressed, to 2 times as wide as thick, (5–)10–40 cm × 0.5–1.2 mm, firm to hard, finely many-ridged at 10–20X;

culm tufts not proximally bulbous.

distal leaf sheaths persistent or decaying, membranous, apex obtuse to acuminate.

distal leaf sheaths stramineous to brown or reddish proximally, green to stramineous distally, subtruncate to obtuse, membranous to papery;

apex brown to red.

sometimes proliferous (when submerged), 9–33 × 1.5–3 mm;

rachilla joints bearing prominent winglike remnants of floral scales;

proximal scale with a flower, amplexicaulous, (5–)6–9.8 mm;

floral scales 4–18, 0.5–1 per mm of rachilla, stramineous to pale brown, often minutely dotted reddish, without or rarely with darker submarginal band, narrowly ovate to lanceolate, 5–7.8 × 2–3 mm, thickly papery, membranous toward margins, apex narrowly rounded to acute.

5–10 × 2–4 mm;

proximal scale usually empty, 3–5 mm, usually 1/2 or more as long as spikelet;

floral scales 8–12 per spikelet, lanceolate (to ovate), 3.5–5 × 2–2.5 mm.

perianth bristles 6–7, stramineous to reddish brown, proximally slightly flattened, subequal to equal, much exceeding to rarely shorter than achene, 3–5 mm, retrorsely spinulose;

anthers yellow to reddish, 1.6–3.2 mm;

styles 3-fid.

perianth bristles 6, equal, the longest equaling achene to exceeding tubercle, very slender, spinules dense;

anthers 1.6–3.5 mm.

stramineous or medium brown, biconvex or compressed trigonous, narrowly obpyriform, 1.9–2.6 × 1–1.4 mm, adaxial face with 15–22 rows of rectangular, transversely elongated or nearly isodiametric cells, clearly sculptured at 10–15X, apex usually conspicuously constricted to short neck 0.4–0.7 mm wide, usually wider at tubercle base.

medium brown to gray or dark brown, equilaterally trigonous to compressed trigonous, rarely some biconvex, 2–2.7 × 0.7–1.3 mm, apex tapered to a distinct stramineous beak 0.2–0.9 × 0.3–0.6 mm.

stramineous to medium brown, high-pyramidal, 0.5–1.1 × 0.3–0.7 mm.

0.4–0.5 × 0.3–0.5 mm.