Winter here is filled with various shades of brown and gray, so anything else stands out. While clearing some downed branches in my yard today, I came across a strikingly blue fungus, the Cobalt Crust Fungus.

Cobalt Crust Fungus

These are the true colors; they really are that striking. The colors range from an intense cobalt blue to black to white. These are growing as crusts on wood. I’ve turned these over; they were originally growing on the bottom side of this wood, against ground that was still damp from the rains last week. I’m not sure what kind of wood these are growing on, but this is from a hardwood forest dominated by Yellow Poplar, Sweetgum, and Southern Red Oak.

Cobalt Crust Fungus

In closeup, the fungus looks somewhat velvety and deepest blue in the center, turning to white towards the edges, being black (dead?) at the edges. Some are cracked, and that may be from drying out.

Cobalt Crust Fungus

The Cobalt Crust Fungus is also called Velvet Blue Spread. Scientifically, it is Terana caerulea, a member of the Phanoerochetaceae family of the Agaricomycetes class of the Fungi. The Agaricomycetes include mushrooms, boletes, and bracket fungi, among others.

The Cobalt Crust Fungus is reportedly found worldwide in warm climates, including the southeast United States. The blue color comes from polymers related to thelephoric acid, and the fungus is used to make the antibiotic cortalcerone, used to treat some streptococcal infections.

I turned these logs back over (fungus-side down, as they should be), so I can check on them later.