Minute, free floating rootless herbs. Fronds symmetrical, thick, ± globular, ellipsoid, not more than 1.5 mm in diameter, veinless, flattened on the upper surface of the water level, daughter thallus produced in a circular lateral pit and soon gets detached from the parent, 1-staminate and 1-pistillate flower in a pit on the upper surface of the median line; spathe absent.