Azolla filiculoides Water Fern

Azolla filiculoides, Water Fern, is a subtropical, free-floating aquatic fern, native to tropical America. Its occurrence in Britain is sporadic, usually ephemeral and unpredicable, but where it does occur it rarely persists and it is intolerant of cold winters. However it is widely distributed in southern Britain and it can be abundant where it does occur. Interestingly, its fronds contain a symbiotic cyanobacterium (Anabaena azollae) which allows it to fix atmospheric nitrogen into combined form and thus colonise nitrogen-poor water. There have been scattered records of Water Fern in West Glamorgan.

Neophyte