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.

0.5–0.7 mm, not winged.

0.6–0.9 mm, laterally winged toward apex.

with 10–16 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, obovate, flat or gibbous, 1–3.5 mm, 1–1.5 times as long as wide, margins entire;

veins 3, greatest distance between lateral veins near middle;

very distinct papillae near apex, some smaller indistinct ones on midline of upper surface;

lower surface very often red colored (more intensely than on upper), coloring beginning at attachment point of root, lower upper surface sometimes with red spots;

air spaces shorter than 0.3 mm; 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, 50.

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