Wolffia arrhiza (Rootless Duckweed / Wortelloos Kroos)

Wolffia arrhiza is the world's smallest flowering plant — a rootless, spherical frond barely 1 mm across that floats as a powdery green film in vast aggregations on the water surface of still to gently moving Dutch and Belgian ditches and sheltered ponds. Sold as a botanical curiosity and highly nutritious live food supplement for koi, goldfish, and waterfowl, it grows prolifically in nutrient-rich water and provides a sustainable live food culture option for pond keepers.

Float on a calm, still water surface with high nutrient levels and full sun exposure. Grows explosively in warm weather — harvest regularly as live food for pond fish. Temperature 4–35°C; frost-hardy perennial. No substrate, CO2, or special care required. Best kept in a separate container or feeding pond to prevent excessive coverage of ornamental pond surfaces. A single tablespoon of culture can produce kilograms of live food within weeks.