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.

emersed, sessile, phyllodial, linear to lanceolate, flattened, 15–25(–40) × 1.5–4 cm, or petiole triangular, 15–50 cm, blade linear to elliptic-lanceolate, 4–10 × 0.3–2 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 3–6 whorls, 1.5 × 4 cm;

peduncle 20–60 cm;

bracts connate greater than or equal to ¼ total length, ovate, 4–10 mm, nearly scarious, not papillose; fruiting pedicels spreading, cylindric, 0.8–3 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 0.8 cm diam.;

sepals recurved to spreading, not enclosing flower;

filaments dilated, exceeding anthers in length, pubescent;

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 1.2–2 cm diam.;

achenes cuneate-obovoid, abaxially keeled, 2.5–3 × 1.4–1.8 mm, beaked;

faces not tuberculate, wings 1, ± entire, glands absent;

beak ascending to horizontal, 0.4–0.7 mm.