Azolla filiculoides Lam.

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Azolla filiculoides

Photo: Bart Wursten
Osborne Dam RP

Azolla filiculoides

Photo: Bart Wursten
Nyamakari River bridge, Burma Valley

Azolla filiculoides

Photo: David Hartung
Lanark Game Park

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Species details: Click on each item to see an explanation of that item (Note: opens a new window)

Common names: Red water fern (English) Water fern (English)
Status: Introduced
Perennial, mat-forming, free-floating aquatic. Rhizomes up to 25 - 35 mm long, branched, bearing roots singly or in clusters of 2-3. Leaves 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; ventral lobe like dorsal lobe but completely translucent. Plant heterosporous.
Notes: 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.
Derivation of specific name: 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
Habitat: In slow-moving water, such as in dams and ditches and slower-flowing parts of streams and rivers.
Altitude range: (metres) Up to 1540 m
Worldwide distribution: Native to tropical South America (Argentina, Brazil, Uruguay and Peru), but now widespread as a weed in Europe, N America, Australia and New Zealand.
Zimbabwe distribution: N,C,E
Growth form(s): Aquatic.
Endemic status:
Red data list status:
Insects associated with this species:
Spot characters: Display spot characters for this species
Images last updated: Wednesday 29 July 2009

Burrows, J.E. (1990). Southern African Ferns and Fern Allies. Frandsen, Sandton. Page 83. (Includes a picture).

Crouch, N.R., Klopper, R.R., Burrows, J.E. & Burrows, S.M. (2011). Ferns of Southern Africa, A comprehensive guide Struik Nature Pages 214 - 215. (Includes a picture).

Henderson, L. (2001). Alien weeds and invasive plants Plant Protection Research Institute Handbook No. 12. Plant Protection Research Institute, Agricultural Research Council, South Africa. Page 19. (Includes a picture).

Jacobsen, W.B.G. (1983). The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 494 - 495. (Includes a picture).

Mapaura, A. & Timberlake, J. (eds) (2004). A checklist of Zimbabwean vascular plants Southern African Botanical Diversity Network Report No. 33 Sabonet, Pretoria and Harare Page 5.

Roux, J.P. (2001). Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report 13 Page 179.

Other sources of information about Azolla filiculoides:

Our websites:

Flora of Mozambique: Azolla filiculoides
Flora of Zambia: Azolla filiculoides

External websites:

African Plants: A Photo Guide (Senckenberg): Azolla filiculoides
African Plant Database: Azolla filiculoides
BHL (Biodiversity Heritage Library): Azolla filiculoides
EOL (Encyclopedia of Life): Azolla filiculoides
ePIC (electronic Plant Information Center): Azolla filiculoides
Flora Zambesiaca web site: Azolla filiculoides
GBIF (Global Biodiversity Information Facility): Azolla filiculoides
Google: Web - Images - Scholar
GRIN (Germplasm Resources Information Network): Azolla filiculoides
iNaturalist: Azolla filiculoides
IPNI (International Plant Names Index): Azolla filiculoides
JSTOR Plant Science: Azolla filiculoides
Kew Herbarium catalogue: Azolla filiculoides
Mansfeld World Database of Agricultural and Horticultural Crops: Azolla filiculoides
Plants of the World Online: Azolla filiculoides
Tropicos: Azolla filiculoides
Wikipedia: Azolla filiculoides

Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2002-23

Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. (2023). Flora of Zimbabwe: Species information: Azolla filiculoides., retrieved 31 January 2023

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