Flora of North America species comparison

present, caudexlike, mostly concealed by crowded culms, vertical or ascending, 2 mm thick;

internodes very short, scales disintegrating to fibers, 4 mm, papery.

erect to ascending or arching, acutely quadrangular, deeply sulcate, 7–50 cm × 0.3–0.5 mm, smooth, firm.

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.

distal leaf sheaths persistent, proximally brown or reddish, distally stramineous to green, thickly membranous, apex acute or subacute.

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

basal spikelets absent; often proliferous, ovoid, terete, 3–10 × 2–3 mm, apex acute;

proximal scale empty, amplexicaulous, similar to floral scales;

subproximal scale with a flower;

floral scales spiraled, 8–15, 4 per mm of rachilla, orange-brown, midrib region broadly stramineous or like flanks, ovate, 2–3 × 1.2–2 mm, membranous, midrib evident to prominent, apex acute (to rounded).

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.

perianth bristles 6 or fewer, stramineous, unequal, some or most equaling achene, spinules obscure, sparse, retrorse, sharply acute.

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.

3;

anthers 1.2–1.5 mm.

3-fid.

stramineous, broadly obpyriform, equilaterally trigonous, angles evident, blunt, 0.9–1.1 × 0.7–0.9 mm, apex nearly truncate, smooth or obscurely papillose or rugulose at 20X.

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.

stramineous, pyramidal, trigonous, usually acute, proximally trilobed, the lobes decurrent on achene, 0.5–0.9 × 0.7–0.9 mm.

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