Azolla filiculoides

Azolla filiculoides Lam. (syn.: A. caroliniana Willd., A. magellanica Willd., A. microphylla Kaulf.) (Am.) – A more or less widely naturalised and increasing alien. First found in 1912 near Bauche (Wallonia) but at present more widespread in Flanders, especially in coastal areas (where frostbite is less likely). Populations are often remarkably unstable and can vary considerably from one year to another.

Additional information on the invasive behaviour of Azolla filiculoides in Belgium is available at:

The exceedingly similar Azolla cristata Kaulf. (syn.: A. mexicana C. Presl) has also been claimed from Belgium. In fact, the first Belgian records of Azolla were ascribed to this species but all records proved to be erroneous (Sotiaux 1979). See however Bernhardt (1991).

Herbarium specimen

Azolla filiculoides

Azolla filiculoides, Dessel, Kempisch Kanaal, standing water, September 2010, R. Barendse.

Selected literature

Bernhardt K.-G. (1991) Zur aktuellen Verbreitung von Azolla filiculoides Lam. (1783) und Azolla caroliniana Willd. (1810) in Nordwestdeutschland. Flor. Rundbr. 25(1): 14-19.

Delay J. & Petit D. (2008) Les espèces aquatiques invasives du Nord de la France et leur biologie. Bull. Soc. Bot. N. Fr. 61(1-4): 5-22.

Hussner A. (2006) Die aquatischen Neophyten in Nordrhein-Westfalen. Decheniana 159: 39-50.

Sotiaux A. (1979) Contribution à une meilleure connaissance du genre Azolla dans le territoire de la Nouvelle Flore. Dumortiera 13: 1-5.

Vanhecke L. (1976) Nieuwe gegevens over de verspreiding van enige water- en moerasplanten in de maritieme polders. Dumortiera 5: 3-14.

Vanhecke L. (2006) Azolla filiculoides. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de Flora van Vlaanderen en het Brussels Gewest. Instituut voor natuur- en bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 175.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith