Azollaceae
Sori borne on a cylindric receptacle on submerged lobe of frond, surrounded by indusium, in pairs: a large globose sorus with numerous long-stalked microsporangia, and an ovoid sorus with one large mega-sporangium with warted epispore. Microspores 64 imbedded in globose massulae bearing branched glochidia. Plants free-floating, stems bearing roots and lvs. Fronds in 2 alt. rows, each with an upper assimilating lobe bearing stomates and a lower thin, submerged lobe bearing paired sori. A family of a single cosmopolitan genus.
