Fl. New York 2: 245. 1843.
Roots to 3.5 cm, tip usually sharp pointed; sheath narrowly winged at base (wing 2–3 times as long as wide). Stipes white, small, often decaying. Fronds floating, 1 or 2–few, coherent in groups, ovate-obovate, flat, 1–4 mm, 1–1.7 times as long as wide, margins entire; veins 3, greatest distance between lateral veins near or distal to middle; 1 distinct papilla near apex on upper surface, 2–3 very distinct papillae above node; anthocyanin absent, no reddish color; air spaces much shorter than 0.3 mm; distinct turions absent. Flowers: ovaries 1-ovulate, utricular scale open on 1 side. Fruits 0.7–1 mm, not winged. Seeds with 35–70 indistinct ribs, staying within fruit wall after ripening. 2n = 40 (U), 42 (G).
Phenology: Flowering (frequent) late spring–fall.
Habitat: Mesotrophic to eutrophic, quiet waters in temperate regions with relatively mild winters
Elevation: 0–600 m
Que., Ark., Conn., Del., D.C., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Minn., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., Tenn., Tex., Vt., Va., W.Va., Wis.
I know of no specimens of Lemna perpusilla from Connecticut or New Hampshire.