Water spangles (Salvinia minima Baker) are small aquatic ferns native to Mexico and South America. They are usually found floating in still waters and form dense mats on the surface where water is nutrient-loaded—polluted with fertilizers or manure. But even in relatively clean water, water spangles make up for their small size by sheer vegetative prowess. In a matter of weeks the ferns will cover the surface of a garden pond. In shady ponds, the tiny oval leaves remain a bright emerald green. In full sun, the leaves take on a reddish bronze cast.

The fern has a greatly reduced anatomy—a thin rhizome that branches freely with three leaves at each node. Two small round to oval leaves that float and a third finely divided leaf that is submerged. The third leaf is often mistaken for roots.

The floating leaves are covered with rows of trichomes (plant hairs). The trichomes on the lower surface are long and rusty colored and serve to discourage fish from eating the leaf. The trichomes on the upper side are light colored and split into four branches. The branched trichomes serve to keep the upper surface of the leaf dry—splashed water forms a bead and is held on the tips of the trichomes. The beaded water sparkles, hence the name "water spangles".

Like other ferns, water spangles produce spores. The spores form in sporocarps that are shaped like miniature limes and hang in a cluster next to the divided leaf. The spores are odd; apparently they are infertile and never germinate. The plants reproduce strictly by the fragmentation of the rhizome and spread to other bodies of water by flooding or carried on the backs of turtles and alligators and on the feet of wading birds.

(Compiled from: "Salvinia minima", Atlas of Florida Vascular Plants, R.P. Wunderlin and B.F. Hansen, Institute for Systematic Botany, University of South Florida, 2004; "Salvinia minima Baker", C.C. Jacono, USGS, US Department of the Interior, 2003)