Anabaena azollae

(from the article `Salviniales`) ...Salvinia having a whorl of three leaves, two of which are round and emergent while the third is submerged and finely divided to function as a ... ...and Pteridium) have been shown to be strongly carcinogenic. The minute, aquatic mosquito fern (Azolla) has become a valuable plant, especially in ... ...
Found on http://www.britannica.com/eb/a-z/a/66
No exact match found