[Azolla bread at Under tallarna. Photo: Erik Sjödin]

The bread above was baked by Under tallarna at their garden party in August 2018. It tasted good but arguably not as great as the same bread baked without Azolla.

The bread was baked with sun-dried Azolla harvested from one of Under tallarna’s watering ponds. As a defence against excessive sunlight the Azolla in the pond had developed a brick-red color. As can be seen in the photo below the red color stays when the Azolla is dried. Azolla that is harvested when it’s green has green-gray color.

The red color comes from deoxyanthocyanins which are antioxidative and generally considered healthy. Azolla also contains minerals, vitamins and possibly other substances which may add to the nutritional value of for example bread. However, wether or not Azolla is healthy to eat remains an open questions. Azolla is an unproven food stuff and there are concerns that cyanobacteria in Azolla may produce neurotoxins. If it’s healthy or not is the key question to resolve with regard to Azolla’s viability as a food stuff, since Azolla generally isn’t a particularly positive addition to the taste of food.

[Sun-dried Azolla at Under tallarna. Photo: Erik Sjödin]

In addition to being a potential food stuff Azolla has many other uses. Under tallarna has been evaluating Azolla as a pond cover throughout the summer of 2018 which has had the hottest July in this area of Sweden since the measurements started in 1756. Their impression is that the Azolla likely has reduced evaporation from the pond. They also experience the water to be cleaner and less warm. Another positive effect is that as the water level in the pond sinks the Azolla sticks to the edges of the pond which help keep the edges moist and reduces cracks in the pond. In another pond they grow duck-weed which also grows well but it doesn’t form a cover as thick as the Azolla. A third pond isn’t covered by plants and the water there is more muddy. Eventually they plan to harvest the Azolla and evaluate as fertiliser and mulch in soil. Previous years they have also evaluated azolla as duck food.

A potential drawbacks of growing Azolla in ponds is that it can completely knock out existing ecosystems since it can cover a water surface completely and block sunlight from other plants and organisms. If a pond is only used as a water reservoar this may not be a concern. It can actually be positive since it can reduce unwanted algae growth and prevent mosquitos from breeding. Of more concern is that Azolla may spread to other ponds and waters. Azolla is an invasive plant and considered a problematic weed in many regions of Europe and the rest of the world. In Sweden Azolla is not yet classified as an invasive species since it’s unlikely to survive the cold winters. If climate change should lead to warmer winters this may change, particularly in the south of Sweden.

[Pond with Azolla at Under tallarna. Photo: Erik Sjödin]