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, phyllodial, lenticular, to nearly terete, 12–53 × 0.3–0.7 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, of 2–7 whorls, floating or emersed, to 16 × 4 cm;

peduncles 13.5–28 cm;

bracts connate more than ¼ total length, ovate to lanceolate, 1.5–2 mm, delicate, not papillose; fruiting pedicels spreading to reflexed in flower and fruit, cylindric, 1.5–6.5 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.

1.5–5 cm diam.;

sepals spreading in staminate, appressed to spreading in flower and fruit in pistillate, often enclosing flower or fruiting head;

filaments dilated, longer than 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 0.4–0.6 cm diam;

achenes oblanceoloid to obovoid, not abaxially keeled, 1.5 × 1 mm, beaked;

faces not tuberculate, wings absent, glands absent;

beak lateral, erect, 1.1 mm.