Schltdl. & Cham. ex Kunze
Azolla mexicana is an aquatic fern native to Mexico, British Columbia and the western United States (California, Oregon, Washington, Arizona, New Mexico, Texas, Utah, and Nevada). There are reports of the species also occurring in the Great Plains of the central United States, but these reports need further study for verification.
Azolla mexicana is a floating aquatic with blue-green to dark red leaves. It is distinguished from the two other species of the genus present in North America (A. caroliniana and A. filiculoides) by having multicellular hairs on the leaves and pits on the megaspores.