Water spangles, water fern
Salvinia plants are floating ferns. There are ten species of salvinia in the world and the water fern, Salvinia minima, is the species that occurs in Florida.
Salvinia plants are floating ferns native to tropical America. There are 10 species of Salvinia in the world, none of which are native to the United States. This species is about 3/4 inch in width. It commonly occurs in freshwater ponds and swamps from the peninsula to the central panhandle of Florida (Wunderlin, 2003).
Free-floating fern; stems rootless, hairy, about 10 cm (4 in) long.
Borne in threes; appear 2-ranked, but with 3rd leaf finely dissected and dangling, resembling roots; rounded to somewhat broadly elliptic, 1–1.5 cm (0.4–1 in) long, with cordate base, upper surface with 4-pronged hairs, lower surface hairy.
In a nutlike sporocarp (a multicellular structure), trailing beneath.
Text from Invasive and Non-Native Plants You Should Know, Recognition Cards, by A. Richard and V. Ramey, 2007. UF/IFAS Center for Aquatic and Invasive Plants, Publ. No. SP 431.
Water fern is about three-quarters of an inch long. It occurs in still water areas with a high organic-matter content. It often grows in association with other aquatic plants. Water fern has joined oval leaves. Its leaf surfaces are covered with stiff hairs. Water fern has root-like structures that are actually modified leaves. These small floating ferns are about three-quarters of an inch long. Water fern has paired, oval leaves with stiff hairs on the leaf tops. It has leaves that look like underwater roots.Water fern has joined oval leaves. Its leaf surfaces are covered with stiff hairs. Water fern has root-like structures which are actually modified fronds.