Common Name: Carbon Balls
Synonyms: King Alfred's Cakes, Coal Fungus, Cramp Balls
Location: Hardwood Forests
Surface Color: Black with age
A fairly common fungus that has a neat aspect that you cannot see on the surface. If you slice these little black balls open, they should have concentric rings that have formed on the inside, much like the rings of a tree. Thus the name "concentrica."
When cut open, aside from the rings, you should encounter a silvery black, possibly purple interior surface. These are also fairly solid mushrooms...they should not be pliable.
7/9/11 - Indiana
This is probably not the true D. concentrica, but another species of Daldinia. Possibly D. childiae, also known as D. concentrica var. minuta. These species are separated by several features, the key field character being the surface turns yellow to yellow-green with KOH. D. concentrica turns purple. The only species you are likely to find in your field guides, however, is Daldinia concentrica.
Two species of Daldinia turn yellow with KOH - Daldinia childiae and Daldinia bakeri. Daldinia childiae has a brownish lighter color to the concentric rings on the interior that has a woody texture while D. bakeri has a whitish to grayish color that is gelitinous and disinegrating. When dry it can form small cavities in the interior. Daldinia childiae also has narrower spores. 12 - 16 x 5.5 - 7.5 vs. 13 - 17 x 7.5 - 8.5 of D. bakeri.
Of the species that turn purple in KOH, D. concentrica is most common on Beech and Ash. D. loculata is most common on Birch.