Lemna perpusilla is a tiny, free-floating, aquatic herb 0.1-0.2 cm long, usually 1-2 times longer than wide, more-or-less egg-shaped (obliquely obovate) and rounded on both sides. Each body (thallus) produces a single unbranched root.
Leaves none. The body is green.
Flowers (use microscope) tiny and rarely produced. Reproduces mostly by budding.
Fruit a utricle – minute, 1-seeded, slightly inflated and thin walled.
Wetland status: OBL.
Frequency in NYC: Very infrequent.