Ferns and Fern Allies in the Canberra Region

Azolla pinnata - Ferny Azolla

Azolla pinnata is a member of a genus of six species of free floating aquatic ferns, and is one of two recorded in the Canberra Region. It grows in dense patches among the reeds along Lake Burley Griffin, among other places. The image to the right shows it growing in a typical location among the reeds. This year there have been large patches of it easily visible from a distance. The individual plants are very small, less that 2.5 cm (1") across. They clump together to blanket open water where they are protected from water movement or wind.

The image to the left shows the patchwork of individual plants. The "fronds" are either a pale green or with reddish patches. In some places the entire plant can be reddish. This is most likely an environmental response, as it seems to occur in places where there is direct sunlight and/or foetid water. A. pinnata differs from a similar species that grows in this region, A. filiculoides, by having lateral-branching roots that dangle in the water below the leaf. It also has fuller, more "fern-like" leaflets.

This image is a close-up of an individual plant, showing the red and green coloration.

The fern occurs in all mainland Australian states. It grows easily in aquarium tanks, especially if encouraged by a little fertilizer.

David Nicholls
October 1999