Azolla
A dense matting of Azolla covering Yabba Creek in Imbil, August 2021
Azolla is a free floating aquatic fern that is often seen taking over large, still bodies of freshwater. This has lead to Azolla earning a somewhat negative reputation and even being classed as a weed despite its native plant status.
Growing Conditions and Spread
Azolla doesn’t require much to thrive, as it’s a fairly low fuss aquatic plant which is how it sometimes earns it’s weed status. Azolla is a genus in the Salviniaceae family and it currently contains 7 species. The species I am most familiar with is Azolla pinnata as it is native to my local region. Azolla is often confused for an algae or slime from a distance, however upon closer observation you can see it’s fern appearance. Azolla pinnata can be either green or red, typically determined by it’s exposure to sunlight (green in the shade, red in direct sun). Azolla replicates readily by fragmentation as well as by spore production, a process that is sped up in nutrient rich bodies of water.
Usage
Azolla can be an incredibly useful resource if you know how to use it. It’s most basic use is the prevention of evaporation in large bodies of water such as a dam. Owing to it’s dense free floating presence on the water’s surface, Azolla can also inhibit mosquitoes from breeding. However thick complete coverings of Azolla can be particularly problematic as it can lead to de-oxygenation of the water, which has a direct impact on other flora and fauna within the water system.
Azolla supports nitrogen-fixing cyanobacterium in it’s fronds that pull nitrogen from the air which is then released as the fern decays. This makes Azolla an ideal fertiliser as well as a mulch that can be applied directly around plants or added to compost heaps.
Azolla is also rich in nutrients, containing up to 30% protein, amino acids and vitamins making it a great fodder plant for animals. We particularly use Azolla for our chickens who simply cannot get enough of it! It can also be cleaned and prepared for human consumption however at this stage as most of what we use is foraged from an overgrown area where cattle live on the creek banks, it is not currently an overly palatable option for us :D
Research has shown Azolla has been around for approximately 50 million years and may have played an important role in C02 sequestration shifting the climate into what we know of the modern world. Further uses of Azolla include processing it into a biofuel as well as in the filtration of kitchen grey water.
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