Synonyms: Azollaceae APNI*
Description: Small aquatic ferns, free-floating; rhizome short-creeping, vernation circinate. Stems dichotomously branched.
Leaves sessile, alternate, small, c. 1–25 mm long, round to oblong, entire.
Spores of 2 types (plants heterosporous), large megaspores and small megaspores, these globose, trilete.
Distribution and occurrence: World: 2 genera, 16 species, widespread in tropical & subtropical regions. Australia: 2 genera, 2 species native, 1 naturalised.
Text by Peter G. Wilson; updated Louisa Murray Jan 2013
Taxon concept: Smith & al. (2006) Fern Classification. Taxon 55(3) 711-712