Cotton candy in the Sihlwald

The mysterious, long and delicate crystals of hair ice, reminiscent of tufts of hair, form exclusively on damp dead wood. There is plenty of it in the Sihlwald natural forest, where dead trees and branches are left lying around. However, not every dead branch forms the special ice shape on cold days.

The main role in the formation of the ice crystals, which are less than a tenth of a millimeter thick, is played by a fungus: only dead wood that is infested by the rose-tinted gelatinous crust (Exidiopsis effusa) forms hair ice. If there is liquid water in the tree, the natural phenomenon grows out of the deadwood like living hair. The fungus ensures that the ice crystals string together like threads.

The "ice cotton candy" forms overnight and only lasts for a short time. Hair ice melts very quickly in the sun. In the shade, it sometimes remains intact for a day. Wind destroys the fine formations immediately. Hair ice is therefore particularly common in shady hollows on windless days. It is always close to the ground. Go in search of it on a cold, damp winter's day in the Sihlwald - it's worth it.

Further information

Bianca Guggenheim
Phone +41 (0)44 722 55 22 (head office)
bianca.guggenheim@wildnispark.ch