Flora of North America species comparison

to 15 cm, tip mostly rounded;

sheath not winged.

to 2.5 cm (sometimes not developed), tip pointed;

sheath not winged.

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

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

0.8–1 mm, laterally winged toward apex.

0.6–0.9 mm, laterally winged toward apex.

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

with 12–18 distinct ribs, staying within fruit wall after ripening.

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.

submersed (except when flowering or fruiting), 3–50, coherent and very often forming branched chains, narrowly ovate, flat, thin, 3–15 mm (excluding stalk), 2–3.5 times as long as wide, base suddenly narrowed into green stalk, margins denticulate distally;

veins (1 or) 3, lateral veins only in proximal part of frond;

papillae absent;

anthocyanin often present;

air spaces shorter than 0.3 mm;

turions absent.

stalks 2–20 mm.

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

= 40, 42, 44, 60, 63, 80.