We have a fish pond at home, and several aquatic plants in it. Two of these are introduced in this article, azolla (on the left) and ludwigia sediodes, a mosaic plant (on the right).

water chest nut or the trapa natans and azolla

Azolla are tiny aquatic ferns, and can be used as a food for livestock, and even humans. One way to use it is by adding it with omelettes 🙂  But make sure you have the azolla from reliable water ponds and not from waste water pools were the aquatic plants may be infected by worms 😛

Azolla are also used to control mosquitos, as it spreads quickly like a mat, over the water surface. I was looking into the literature on Azolla, and was astounded by a recent (2006) study published in the scientific journal Nature, on the possible role played by it during the Eocene period, around 49 million years ago. The study by Brinkhuis et al. pointed out that azolla may have had a significant role in reversing a greenhouse warming effect that had caused the region around the Arctic Ocean to turn into a hot, tropical environment.

The potential of Azolla as a space diet has also been studied! Check the references and links below if you want to know more about these studies on Azolla.


The seeds of the ludwigia sediodes is also used as a food (?). We haven’t but noticed the seeds yet though we got a lot of flowers from the plant, like the small yellow flower you see in the picture above. Probably they need to grow wild and large for that. We love the mosaic plant, its rosette shape is so beautiful, especially when it spreads and lie majestically over the water surface. During night time the leaves droop together like the petals of a flower. The mosaic plant shown here is a foeigner, and there is a type endemic to the Indian region. We saw the Indian version at an aquatic garden/farm (under the Guruvayurappan college or Calicut University, I don’t remember now) at Kozhikode, Kerala. I think it is not that common.

velvet mite on a water chestnut

velvet mite on azolla

Sometimes we have visits from our non aquatic friends, like the red velvet mite [Family: Trombidiidae] above. You can see that they are so tiny, if you have an idea of the size of azolla, or comparing the images above. Velvet mites are not insects, but belong to the class of arachnids [Class: Arachnidea] which includes spiders, scorpions and other mites too, with the usual 8 legs.

Date: Jan 2008
Location: @ home, Kottayam, Kerala, India
Camera: Nikon D80 | Olympus C770UZ

1. Brinkhuis et al., 2006: Episodic fresh surface waters in the Eocene Arctic Ocean, Nature, 441, 606-609 [
2. Katayama et al., 2008: Azolla as a component of the space diet during habitation on Mars, Acta Astronautica, 63, 7-10 [

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