Flora of North America species comparison

septate.

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.

sessile or petiolate;

petiole terete to triangular;

blade with translucent markings absent, linear to obovate, base attenuate to hastate or sagittate, margins entire, apex round to acute.

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, panicles, rarely umbels, of 1–17 whorls, erect, emersed or floating, rarely submersed;

bracts coarse or delicate, apex obtuse to acute, smooth or papillose proximally to distally.

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.

unisexual, the proximal rarely with ring of sterile stamens;

staminate flowers pedicellate, distal to pistillate flowers;

pistillate flowers mostly pedicellate, rarely sessile;

bracts subtending pedicels, lanceolate, shorter than pedicels, apex obtuse to acute;

pedicels ascending to recurved;

receptacle convex;

sepals recurved in staminate flowers, recurved to erect in pistillate flowers, often sculptured, herbaceous to leathery;

petals white, rarely with pink spot or tinge, entire;

stamens 7–30;

filaments linear to dilated, glabrous to pubescent;

pistils to 1500 or more, spirally arranged, not radiating in starlike pattern, distinct;

ovules 1;

styles terminal.

without longitudinal ribs, compressed, abaxially keeled or not, abaxial wings often present, lateral wing often present, 1, curved, glands present.

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.

= 11.