Flora of North America species comparison

septate or not septate.

emersed, floating, and submersed; submersed phyllodial, flattened, to 45 cm; floating with petiole triangular, to 100 cm, blade cordate or sagittate, rarely linear or ovate, 7.5–9 × 3.5–4 cm; emersed with petiole recurved, 3.5–51 cm, blade linear to sagittate, 2.5–17 × 1.5–11 cm, basal lobes when present shorter than remainder of blade.

basal, submersed, floating, or emersed, sessile or petiolate, sheathing proximally;

blade with translucent markings of dots or lines present or absent, basal lobes present or absent;

venation reticulate, primary veins parallel from base of blade to apex, secondary veins reticulate.

racemes, rarely panicles, of 2–10 whorls, emersed, 14–21 × 2–10 cm, peduncle triangular, 10–50 cm;

bracts connate more than or equal to ¼ total length, lance-attenuate or acute, mostly (4–)7–40 mm, membranous, not papillose; fruiting pedicels ascending, cylindric, 0.5–2 cm.

scapose racemes or panicles, rarely umbels, erect, rarely floating or decumbent, whorled (forming racemes) or whorls branching (forming panicles), bracteolate.

to 25 mm diam.;

sepals recurved, not enclosing flower or fruiting head;

filaments not dilated, equal to or longer than anthers, glabrous;

pistillate pedicellate, without ring of sterile stamens.

bisexual or unisexual, if unisexual, staminate and pistillate on same or different plants, hypogynous, subsessile to long-pedicellate;

sepals persistent, 3;

petals deciduous, 3, delicate;

stamens 0, 6, 9, or to 30, distinct;

anthers 2-loculed, dehiscing longitudinally;

pistils 0 or 6–1500 or more, distinct or coherent proximally, 1-loculed;

placentation basal;

ovules1–2.

achenes or follicles.

embryo U-shaped;

endosperm absent in mature seed.

heads 0.8–1.5 cm diam.;

achenes obovoid, abaxially keeled, 1.8–2.6 × 1.3–2.5 mm, beaked;

face not tuberculate, wings 0–1, ± entire, glands 0–1;

beak apical, erect, 0.1–0.4 mm.

= 22.