Red water fern Water fern

Rhizomes horizontal, branched, up to 25-35 mm long, bearing roots singly or in clusters of 2-3. Leaves closely overlapping, 2-lobed, each lobe 0.5-1.5 mm long, silvery-green, turning red in winter; dorsal lobe broadly ovate to almost circular, apex rounded, margin translucent, thickly papillate; ventral lobe like dorsal lobe but completely translucent. Plant heterosporous.

A fairly frequent well-naturalised species. It differs from A. nilotica in having 1-3 roots per node whereas A. nilotica has numerous (5 or more) roots per node. The other native Azolla, A. pinnata, has 2-3 roots per node, but the plant is more noticeably pinnate, the leaves are smaller and more acute at the apex and the plant is never reddish.
Recent literature (Roux et al., 2011) describes the resemblance of A. filiculoides to another introduced species in South Africa, A. microphylla. A. microphylla has ± dichotomously branched rhizome (irregular, not noticeably pinnate in A. filiculoides) and roots that are hairy & not curled at the tip (not hairy & curled at the tip in A. filiculoides). More research to establish wether A. microphylla also occurs in Zimbabwe is needed.

filiculoides: resembling a fern (from the Latin, filicum for a fern); unclear reference since Azolla does not coincide with the image that one has of a fern.

In slow-moving water, such as in dams and ditches and slower-flowing parts of streams and rivers.

Africa; native to tropical S America (Argentina, Brazil, Uruguay and Peru), but now widespread as a weed in Europe, N America, Australia and New Zealand.

Egypt, Lesotho, Morocco and Western Sahara, South Africa, Zimbabwe.

Aquatic.