minute aquatics, free floating. Frond 1 or 2, coherent together, symmetric,
globose, ovoid or boat-shaped, never reddish, margins entire, or papillate,
nerves and roots absent. Budding pouch basal, median, funnel-shaped, with
circular opening and with a rudimentary stipe. Inflorescence 1, dorsal,
consisting of a cavity containing 1 male and 1 female flower, without a spathe,
proterogynic. Stamen 1, anther unilocular. Female flower consisting of a globular ovary with a
short persistent style. Ovule 1, orthotropous. Fruit globular. Seed 1, globose
or slightly compressed, smooth.