Nature
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Ever noticed the appearance of mysterious and jelly-like green blobs or mats on your lawn or driveway after a rainy day? No, it’s not aliens, nor has someone done a very big sneeze near your house – it might just be Nostoc.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.What is Nostoc?
Also known as troll’s butter or star jelly, Nostoc is a genus of cyanobacteria that can often form big, gelatinous colonies. Such colonies can be found in a wide range of habitats, including in water and on land, with some species known to form symbiotic relationships with plants in these places.
Conquering both the land and sea is impressive enough as it is, but Nostoc species are also masters of survival. They can photosynthesize, fix nitrogen, withstand being frozen and thawed multiple times, and absorb UV radiation – all of which helps them to survive in even the most extreme of habitats, from the tropics to the poles.
Nostoc can also persist in acutely dry conditions for months or even years; this is known as desiccation. In the case of the widespread Nostoc commune, colonies shrivel up and turn dark brown or black, meaning they easily blend in with the places they typically inhabit, like parking lots or soil.
You’d be forgiven for thinking it was just some leaf litter, which is perhaps why Nostoc seems to pop up out of nowhere once it’s been rehydrated.
Is Nostoc harmful?
Some species of cyanobacteria produce toxins, Nostoc included. However, as Joe Boggs, an assistant professor at Ohio State University’s Department of Extension, explained in a blog post, “Nostoc commune and other mat-forming members of this genus are not toxic; they cause no harm to plants or animals.”
That includes humans, who have been making use of the unusual blobs for hundreds of years. Nostoc commune, for example, has long been used as a foodstuff in multiple countries, including China, Indonesia, and Peru, where it is eaten on its own or in dishes like stews. Similarly, Nostoc flagelliforme, also known as fat choy, is considered to be a delicacy in Chinese cuisine, and is often consumed during the Lunar New Year.
Due to its nature as an extremophile, growing Nostoc species has also been proposed as a solution to some of the challenges of settling space; proponents have suggested the cyanobacteria could be used as a source of both oxygen and food.
All that being said, there’s one particular circumstance where Nostoc can easily become a health hazard. If you have some on your lawn or pavement, it’s probably a good idea to dodge it, because it’s super slippery when wet.
Then again, if you do fall on it, at least you’ll have a nice, slimy snack within reach.
