Description: This little fern floats on the surface of ponds or lakes with its roots hanging down into the water. It is an American species introduced as a plant for garden ponds from which it has escaped into watercourses and lakes around the Province, including Lough Neagh. The plant has become very abundant in some of these lakes in the last ten years or so and its survival over winter in the wild may have been helped by a rise in average winter temperatures in Northern Ireland. Sometimes it can completely cover the surface of a pond and forms dense masses of material washed up on the Lough Neagh shores in the autumn.

All names: Azolla filiculoides Lam.

Distribution Map from NBN: Azolla filiculoides at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Azolla filiculoides at iNaturalist World Species Observations database.