Flora of North America species comparison

shorter than 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.

0.5–0.6 mm, not winged.

0.6–0.9 mm, laterally winged toward apex.

with 30–60 indistinct 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–few, coherent in groups, obovate, scarcely gibbous, flat, 1–4 mm, 1–1.5 times as long as wide, margins entire;

veins 3, greatest distance between lateral veins near or distal to above middle;

papillae distinct on midline of upper surface (apical papilla scarcely larger than others);

lower surface often red (more intensely so than on upper), coloring beginning at attachment point of root, upper surface (especially near apex) sometimes with red spots;

air spaces to 0.3 mm;

turions sometimes present, rootless, olive to brown, 0.8–1.6 mm diam., sinking to bottom.

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 (G), 50, 80.

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