Azollaceae

Azollaceae is a family of tiny ferns that float on water, commonly known as the mosquito fern. This family contains a single genus, Azolla, which has six species. These ferns are characterized by their small, branching stems and two-lobed leaves. A notable feature of Azolla is its symbiotic relationship with the blue-green alga Anabaena azollae. The alga provides nitrogen to the fern, a process known as nitrogen fixation, which has made Azolla valuable in rice cultivation, especially in Asia. While Azolla has roots, another related genus, Salvinia, lacks them.12