Editing Azolla (section)

==Invasive species==
This fern has been introduced to other parts of the world, including the United Kingdom, where it has become a pest in some areas. A nominally tropical plant, it has adapted to the colder climate. It can form mats up to {{convert|30|cm}} thick and cover 100% of a water surface, preventing local insects and amphibians from reaching the surface.<ref>{{Cite web|url=https://insideecology.com/2017/11/01/invasive-non-native-species-uk-water-fern/|title=Invasive non-native species (UK) – Water fern|date=November 1, 2017|website=Inside Ecology}}</ref>

''Azolla filiculoides'' is especially invasive because it has the ability to survive temperatures as low as {{convert|-22|C}} and can survive thin layers of ice built up on its growth. ''A. filiculoides'' spreads at rapid pace by way of [[Fragmentation (reproduction)|Fragmentation]] which takes place in the rhizome (root-system). It can double its surface area and/or density in approximately 7-10 days under ideal conditions.<ref name="Weber-2017"/>

''A. filiculoides'' disrupts aquatic ecosystems by altering abiotic conditions in the water. It can displace native plants in places where it is invasive, such as the duckweed ''[[Lemna minor]]'' in Poland. It is difficult to control due to its ability to reestablish itself from spores. <ref name="Weber-2017"/>