malformalady:

Hair ice, also called silk frost, is a type of ice formation that looks like silky hair and seems to only appear on woody, barkless materials on the ground. The ice structures tend to grow out of a small pore in the wood, sort of like hairs on the human head. Hair ice, is ice that grows outward from the surface of the wood, as super-cooled water emerges from the wood, freezes and adds to the hairs from the base.