It’s hairy, it’s a hundred years old and it produces beautiful hair ice. Could it possibly be nicknamed ‘Gandalf’ after the famous white-bearded wizard from Lord of the Rings? Scientists have discovered a species of fungi that, under specific optimum conditions – sprouts hair ‘ice’ to grow on rotten branches of trees. Sounds like Elsa from Frozen has been messing around in the forest again…
The Exidiopsis effusa fungus had been the “missing ingredient”, researchers said in a paper that has been published in the European Geosciences Union’s open access journal Biogesciences.
The phenomenon of ‘hair ice’ has confounded boffins for nearly a century, which thrives on dead wood during humid winter nights when air temperatures drop a little below zero degrees centigrade.
A crack team of scientists in Germany and Switzerland believe they have now cracked the code 96 years after continental drift man Alfred Wegener first studied the white, silky hairs found on crumbling tree branches.
“When we saw hair ice for the first time on a forest walk, we were surprised by its beauty,” said Christian Mätzler from Switzerland’s Institute of Applied Physics at the University of Bern.
“Sparked by curiosity, we started investigating this phenomenon, at first using simple tests, such as letting hair ice melt in our hands until it melted completely.”
Wegener had hypothesized that a relation existed between the ice and the type of fungus found in the wood.
However, it’s taken nearly 100 years to nail down the phenomenon due to hair ice’s “rare and fleeting” appearance mainly in broadleaf forests. It also grows mostly at night and vanishes at sun rise.
During research in Germany carried out by bioloist Gisela Preuß, who collected hair-ice-bearing wood during the winters of 2012, 2013 and 2014, eleven different types of fungi were discovered from the samples.
She said: “One of them, Exidiopsis effusa, colonized all of our hair-ice-producing wood, and in more than half of the samples, it was the only species present.”
Mätzler, meanwhile, was examining the physics of hair ice on samples he collected in a forest in Switzerland. He found that ice segregation seemed to be the driving force for producing ice filaments at the wood surface.
The EGU explained:
Liquid water near the branch surface freezes in contact with the cold air, creating an ice front and “sandwiching” a thin water film between this ice and the wood pores.
Suction resulting from repelling intermolecular forces acting at this “wood-water-ice sandwich” then gets the water inside the wood pores to move towards the ice front, where it freezes and adds to the existing ice.
If the fungal activity is missing from the dead wood, then the type of ice that forms on the tree tends to be a “crust-like structure”, said Mätzler.
“The action of the fungus is to enable the ice to form thin hairs – with a diameter of about 0.01 mm – and to keep this shape over many hours at temperatures close to 0°C. Our hypothesis includes that the hairs are stabilized by a re-crystallization inhibitor that is provided by the fungus,” he added.
If you ask me, the hair ice looks uncannily similar to Gandalf’s hair…