Flora of North America species comparison

submersed or emersed; submersed leaves phyllodial, angled abaxially, flattened adaxially, 6.4–35 × 0.5–4 cm; emersed with petiole triangular, 6.5–17 cm, blade linear to linear-oblanceolate, 2.5–17.4 × 0.2–4 cm.

submersed and floating, sessile, phyllodial, flattened, 50–250 × 0.4–1.5 cm;

rare stranded plants without expanded leaf blades.

racemes or panicles, of 1–12 whorls, emersed, 2.5–21 × 1–8 cm;

peduncles 6.5–29.7 cm;

bracts connate more than to equal to ¼ total length, broadly subulate to lanceolate, 20–50 mm, coarse, not papillose; fruiting pedicels spreading, cylindric, 0.5–5 cm.

racemes, rarely panicles, of 4–10 whorls, floating to slightly emersed, 15–25 × 5–15 cm;

peduncles to 200 cm;

bracts connate less than or equal to total length, lanceolate, 0.4–0.8 mm, delicate, not papillose; fruiting pedicels spreading to recurved, cylindric, 1.5–4.5 cm.

to 2.3 cm diam.;

sepals recurved to spreading, not enclosing flower;

filaments dilated, shorter than anthers, pubescent;

pistillate flowers pedicellate, without ring of sterile stamens.

to 2.8 cm diam.;

sepals erect to spreading in staminate, erect in pistillate, enclosing flower or fruiting head;

filaments dilated, ± equaling anthers, glabrous;

pistillate pedicellate, without ring of sterile stamens.

heads 0.6–1.5 cm diam.;

achenes oblanceoloid, without abaxial keel, 1.5–2.8 × 1.1–1.5 mm, beaked;

faces not tuberculate, abaxial wings 0–1, ± entire, glands 1–2;

beak lateral, erect, 0.2 mm.

heads 0.7–1 cm diam.;

achenes obovoid, abaxially keeled, 5 × 2.5 mm, beaked;

faces not tuberculate, wings absent, glands 0–1;

beak lateral, erect, 1 mm.

= 22.