Water spangles

Care at a glance

Overview

An easy, undemanding floater for the surface that does well in low to moderate light with no CO2 and minimal fuss. Just scatter it on the surface; it needs still water and will rot or sink under heavy spray and surface flow, so keep filter agitation low. It multiplies quickly and shades the tank below, so skim out excess regularly. Be aware it is a recognized invasive species and is listed as a prohibited noxious plant in Texas (and regulated in several other states), so never release it and bin all trimmings.

In the wild

A small floating fern native to South America, Mesoamerica, and the West Indies, growing on the surface of still ponds, ditches, and slow streams. Pairs of oval green leaves about half a centimeter to two centimeters across float on the surface while a third, finely divided submerged leaf hangs below and works like a root. Introduced to the southern United States in the 1920s and 1930s, it has spread widely and forms dense surface mats.

Good to know

Salvinia minima is a true fern (family Salviniaceae, order Salviniales), so it reproduces by spores and fragmentation rather than flowers or seeds, and most aquarium-grown plants are sterile and spread only by breaking apart. The upper leaf surfaces are covered in fine water-repelling hairs that branch into four points but do not meet at the tips, distinguishing it from the much more dangerous giant salvinia. It is rootless; the dangling dissected leaf takes the place of true roots.

Did you know

Did you know the tiny eggbeater-shaped hairs on its leaves trap a layer of air that makes the plant nearly impossible to wet? That same trick on its giant relative inspired engineers studying drag-reducing, self-drying surfaces.

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