Azolla wani nau'in fern ne na ruwa wanda ke cikin dangin Salviniaceae. Wadannan ferns ƙanana ne kuma suna shawagi a saman jikunan ruwa masu tsayayye ko a hankali, kamar tafkuna, tafkuna, da ramuka. Tsire-tsire na Azolla suna da ƙananan ganye masu launin kore masu kama da ma'auni, kuma yawanci ana amfani da su azaman taki na halitta don shinkafa shinkafa. Kalmar "Azolla" ta samo asali ne daga kalmar Helenanci "azotos," wanda ke nufin "ba tare da nitrogen ba," yana nuna ikon fern na gyara nitrogen na yanayi zuwa nau'i mai amfani da wasu tsire-tsire.