Azolla is a genus of seven species of aquatic ferns in the family Salviniaceae. It is a unique freshwater fern that is one of the fastest-growing plants on the planet due to its symbiotic relationship with a cyanobacterium called anabaena. Anabaena draws down the atmospheric nitrogen that fertilizes Azolla, and Azolla provides a nitrogen-filled home for anabaena within its leaf cavities. This enables the plant to double its biomass in as little as two days free-floating on water as shallow as one inch. Azolla is highly productive and can double its biomass in as little as 1.9 days, depending on growing conditions, and yield can reach 8–10 tonnes fresh matter/ha in Asian rice fields. Azolla is commonly grown as a bio-fertilizer for wetland paddies, and it has been used for at least one thousand years in rice paddies as a companion plant to fix nitrogen and to block out light to prevent competition from other plants.

Azolla is also finding increasing use for sustainable production of livestock feed. It is rich in protein, essential amino acids, vitamins, and minerals. Studies describe feeding Azolla to dairy cattle, pigs, ducks, and chickens, with reported increases in milk production, weight of broiler chickens, and egg production of layers, as compared to conventional feed. Fish can also feed on Azolla, as it is quite nutritional for them. Azollas rapid growth makes it a potentially important sequester of the greenhouse gas carbon dioxide, which is converted directly into Azollas biomass. This provides local livestock feed, biofertilizer, food, and biofuel wherever Azolla is grown, so that this remarkable plant has the potential to help us weather the Perfect Storm – the related threats of man-made climate change and shortages of food and land as our population passes seven billion.