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.

often ascending, often spotted or streaked red-brown, cross section quadrangular or broadly elliptic, often sulcate, 1.5–8(–25) cm × 0.1–0.3 mm, soft.

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

distal leaf sheaths persistent or fugaceous, closely sheathing, not conspicuously wrinkled, colorless or pale brown, sometimes spotted red-brown, delicately membranous, apex narrowly acute.

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.

basal spikelets absent; never proliferous, ovoid or ellipsoid, laterally compressed or terete, 1.5–3.7 × 0.8–3 mm, apex acute;

proximal scale empty, persistent, amplexicaulous, similar to floral scales;

subproximal scale with a flower;

floral scales distichous (spirodistichous), 8–22, 6–10 per mm of rachilla, colorless or pale brown, mottled red-brown to purple, ovate, (1–)2 × 1 mm, membranous, midribs green and red-brown, prominent, apex rounded to obtuse.

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 present or absent, (1–)4, colorless to white, vestigial to shorter than achene, 0–0.55 mm;

spinules not evident at 45X;

stamens (1–)3;

anthers 0.35–0.45 mm;

styles 2-fid (or 3-fid).

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.

whitish to pale brown, obovoid, biconvex, rarely trigonous, angles prominent, 0.5–0.8 × 0.4–0.6 mm, apex slightly constricted proximal to tubercle, smooth.

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

sessile, green or red-brown, pyramidal, birettaform or umbonate, 0.15–0.25 × 0.3–0.4 mm.