3. Wolffia Horkel (watermeal)

Plants minute, of 1 or 2 unequal, connected fronds, sometimes producing turions. Roots absent. Fronds 0.4–1.0 mm long, globose or ovoid, flat or concave above in some species, green or with red or brown spots. Veins absent. Pouches 2 per frond, the one along the margin of the frond producing vegetative buds, the one on the upper surface producing flowers. Fruits 0.3–0.6 mm long, lacking wings, the seed lacking ribs. Eight species, worldwide.

Wolffia contains the smallest flowering plants known. Magnifications of 10¥ or higher are necessary to separate the species.