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.

mostly submersed, rarely emersed, sessile, phyllodial, flattened to lenticular, 5–30 × 0.2–0.5 cm.

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 2–5 whorls, emersed, 1.5–8 × 1–7 cm;

peduncles 1–2.5 cm;

bracts connate more than or equal to ¼ total length, lanceolate, 0.5–1.5 mm, delicate, not papillose; fruiting pedicels spreading, cylindric, 0.6–2.5 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 2.5 cm diam.;

sepals recurved to spreading, not enclosing flower or fruiting head;

filaments dilated, shorter than anthers, minutely tomentose;

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 0.5 cm diam;

achenes obovoid-triangular, abaxially keeled, 2 × 1 mm, beaked;

faces tuberculate, wings 1, scalloped or toothed, glands 0–1;

beak lateral, incurved-erect, 0.3 mm.