Flora of North America species comparison

2–40 cm × 0.5–1.5(–2) mm.

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.

apex of distal leaf sheath obtuse to acute, tooth to 0.3 mm.

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

lanceoloid to subcylindric or ovoid, 5–10(–20) × 2–3(–4) mm, apex acute (to rounded);

proximal scale empty, encircling ca. 2/3 of culm;

floral scales 25–100(–200), 8–12 per mm of rachilla, orangebrown to stramineous, 2(–2.5) × 1–1.3 mm, midribs mostly keeled, ovate, apex narrowly rounded to subacute.

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 present or often absent, 5–8, brown, stout, rudimentary to slightly exceeding tubercle;

stamens (2–)3;

anthers brown to yellow, 0.3–0.7(–1) mm;

styles 2–3-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.

0.9–1.1(–1.5) × 0.7–1.1 mm.

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.

depressed, subdeltoid, 0.1–0.3(–0.4) × 0.6–0.9(–1) mm, 1/10–2/5 as high as wide, 1/4 or less as high as achene, 9/10 as wide as achene, very rarely 2/5 as high as achene (in E. engelmannii var. robusta).

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

= 10.