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Submerged, rhizomatous perennial; turions absent; stems erect, short, to 5 (–8) cm long. Leaves to 15 cm long, 0.5 mm wide, acute or obtuse. Inflorescence remaining below water surface during flowering and maturing with a peduncle usually less than 5 (–10) cm long; peduncle not coiled but often recurved in fruit. Flowers 2, with 2–5 carpels; carpels initially subsessile, but stipe lengthening as carpel matures until it is longer than the carpel. Fruiting carpels flask-shaped, almost cylindric, 2–4 mm long, 1–1.5 mm wide; endocarp beak to 0.5–1 mm long with narrowly ovate to ovate perforation on each side.
Rhizome 0.2-0.4 mm wide, the internodes to 1.5 cm long. Stems to 1 m long, 0.3-0.6 mm in diameter, erect. Leaves to 1 dm long; sheaths 7-14.5 mm long and to 1.1 mm wide; blades 0.2-1.0 mm wide, 1-nerved, the apex acute with several minute teeth. Winter buds absent. Inflorescence a 2-flowered spike. Flowers with anthers 0.5-0.7 mm long and 0.5-0.6 mm wide; carpels 4-5, ca. 0.5 mm long and ca. 0.1 mm wide. Fruits 1.2-1.9 mm long and 0.7-1.2 mm wide, beak 0.6-0.8 mm long, stipe 2-6.5 mm long and ca. 0.2-0.4 mm wide.
Stems elongated, densely branched. Leaves 2-10 cm × ca. 0.5 mm, with conspicuous midvein, apex acuminate or acute; sheaths 2-10 × ca. 0.4 mm. Spikes 2-flowered, 2-4 cm; peduncles filiform, shortly accrescent after anthesis. Anthers elliptic. Carpels 4-6. Fruitlets obliquely ovoid, ca. 2(-3) × 1.5 mm, beak ca. 0.2 mm, with a stalk 0.5-1.7 cm. Fl. and fr. Apr-Jun. 2n = 20, 40.
Perennial herb, graminoid, hydrophyte; height depending on depth of water. Leaves alternate, opposite at top, apices acute; sheaths narrow. Scape usually short, twice as long as fruiting pedicels, bright green. Flowers bisexual, naked, protandrous; stamens opposite; carpels usually 4. Flowering time Jan., Feb. Fruit a drupe or nutlet, oblique.
. Stem to 8 dm; lvs 3–10 cm × 0.5 mm; fr 2–3 mm; 2n=14, 16, 20, 24, 28, 40. Interruptedly cosmopolitan; along both coasts of the U.S. in saline or brackish (rarely truly marine) water, and scattered inland in saline or brackish (rarely fresh) water. Highly variable, and by some authors divided into several apparently confluent spp. or vars.
Aquatic, grass-like, perennial herb. Leaves with blade linear to filiform, apex acute, bright green. Flowers: on short, 8-26 mm long, straight peduncles; Sep.-Mar. Fruit 2.0-2.8 mm long with short beak; fruiting scape usually short and recurved, occasionally up to twice as long as fruiting stipes.
Stems to 50 cm × 0.1--0.7 mm. Leaves 6--10.5 cm; blade 0.3--0.5 mm, apex ± obtuse. Inflorescences: peduncles with 0--3[--4] coils, 0.5--16.5 × 0.5 mm. Flowers: pistils 4--8. Fruits 1.8--2 × 0.7--1.5 mm; gynophore 1.2--1.9 cm; beak terminal, slightly recurved, 0.6--1 mm. 2n = 16.
Submerged, green or brownish, grass-like aquatic perennial with slender, cylindrical, branched stems. Leaves linear to filiform, gradually narrowed to a fine point. Flowers in a small spike on short, slender, straight peduncles.
Leaves acute; scape usually short and straight not more than about twice as long as the fruiting pedicels; otherwise characters of the genus.
Submerged, grass-like aquatic perennial. Leaves linear to filiform, acute. Flowers on short, straight peduncles.
