family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
fern
The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...
s in the order
Salviniales
The order Salviniales (formerly known as the Hydropteridales and including the former Marsileales) is an order of ferns in the class Polypodiopsida.
Description
Salviniales are all aquatic and differ from all other ferns in being heterosporous, ...
. The Salviniaceae contain the two genera '' Azolla'' and ''
Salvinia
''Salvinia'' or watermosses is a genus of free-floating aquatic ferns in the family Salviniaceae. The genus is named in honor of 17th-century Italian naturalist Anton Maria Salvini, and the generic name was first published in 1754 by French bo ...
'', with about 20 known species in total. The oldest records of the family date to the Late Cretaceous. ''Azolla'' was previously placed in its own family, Azollaceae, but research has shown ''Azolla'' and ''Salvinia'' to be sister genera with the likely phylogenic relationship shown in the following diagram.