pond fern, mosquito fern, water velvet
Could be confused with
not likely to be confused with any other plant genus
Species commonly cultivated
Azolla caroliniana Willd. (America)
A. filiculoides Lam. (America, Africa, Asia to New Caledonia)
A. mexicana Schlecht. & Cham. ex K. Presl. (America)
A. nilotica Mett. (Africa)
A. pinnata R. Br. (Asia to New Caledonia)
U.S. Federal Noxious Weed: Azolla pinnata
Identification: Diagnostic characters: vegetative: triangular shape of plants, feathery appearance of roots; sexual: megasporangium has 9 floats; microsporangial massulae have no glochidia, but have vacuolated trichomes.
small, free-floating, with tiny, crowded, bilobed leaves
Annual or perennial water fern. Stem floating, more or less pinnately branched. Roots simple, with root hairs present or absent at nodes. Leaves in two alternate rows, overlapping and covering stem, divided into two lobes; upper lobe aerial, thickened and photosynthetic (red or green colored), lower lobe submersed and non pigmented. A thin-walled pouch forms on the upper lobe, enclosing cavities containing nitrogen fixing cyanobacteria (Anabaena azollae Strasb.). Sporocarps borne in pairs in leaf axils of older branches; megasporocarps small, containing a single megaspore; microsporocarps with many microsporangia. Dispersal by spores or stem fragments.
still waters of all types of water bodies