Flora of North America species comparison

to 15 cm, tip mostly rounded;

sheath not winged.

1 per frond.

ovaries 1-ovulate, utricular scale with narrow opening at apex.

1(–2) per frond, surrounded by small utricular, membranous scale;

stamens 2, 4-locular.

0.8–1 mm, laterally winged toward apex.

with 8–15 distinct ribs, staying within fruit wall after ripening.

1–5, longitudinally ribbed.

white, small, often decaying.

floating, 1 or 2–5 or more, coherent in groups, ovate, scarcely gibbous, flat, 1–8 mm, 1.3–2 times as long as wide, margins entire;

veins 3(–5) (if more than 3, outer ones branching from inner ones), greatest distance between lateral veins near or proximal to middle;

papillae not always distinct (one near apex usually larger);

lower surface very seldom slightly reddish (much less than on upper), coloring beginning from attachment point of root, upper surface occasionally diffusely reddish;

air spaces 0.3 mm or shorter; distinct turions absent.

floating or submersed, 1 or 2–20 or more, coherent in groups or forming chains, lanceolate-ovate, flat or gibbous, 1–15 mm, margins entire or denticulate, upper surfaces sometimes with small conic papillae along veins (especially at node and near apex);

air spaces in tissue;

reproductive pouches 2, lateral, at base from which daughter fronds and flowers originate, triangular;

veins 1–5(–7), originating from point in proximal part of frond (node) or if more than 3 veins present, outer ones sometimes branching distally from inner ones;

scale at base of frond absent;

anthocyanins sometimes present;

pigment cells absent (red pigmentation present in some species);

turions absent (sometimes present in L. turionifera).

= 10, 21, 22

= 40, 42 (B), 50, 63, 126.