796.000 Wolffia Horkel ex Schleid.

Minute, floating aquatics with thalli usually less than 1 mm. Roots 0. Thalli solitary or 2 cohering, inflated, globular; nerves 0. Budding pouch 1. Inflorescence of 1 female and 1 male flower without a membranous spathe. Anther 1-thecous. Fruit 1-seeded. Seed up to 0.5 mm, spherical, smooth and spongy.

Worldwide: c.7 species, ± cosmopolitan but not in colder areas