Jelly fungi belong to several orders within the subphylum Agaricomycotina, and are identifiable by the jelly-like consistency of their fruiting bodies, although they range widely in color and shape.   This particular specimen found at a conservation area in Mashpee was rubbery and gelatinous (Think: the consistency of a gummy bear). Although many jelly fungi will shrivel and dry up if there is an extended period with no rain, when exposed to water they will return to their original form; they have the ability to absorb up to 60 times their weight in water, allowing them to transform from tiny dried up bumps to bulbous gelatinous shapes in no time.

Although it is difficult to positively identify exactly what species of jelly fungus this is, my guess would be that it’s Exidia glandulosa, also known by the common names of black witches’ butter, black jelly roll, or warty jelly fungus. It certainly fits the description of E. glandulosa, which is a common wood rotting fungus throughout Europe and North America, often found on dead or decaying oak branches as this one was.  Other identifying features, which lead me to believe it is E. glandulosa, include:

• Fruiting bodies are sepia to black and disc-shaped, although their shape will warp and distort with age.
• The upper surface of fruiting bodies is dotted with small pimples.
• Fruiting bodies are approximately 1 to 1.5 inches in diameter.
• Fruiting bodies are often produced in the fall and winter.

Because jelly fungi only attack the dead and rotting portions of the tree, the healthy tissues of the tree are not in danger of being damaged.  Although E. glandulosa often persists on fallen branches, the presence of jelly fungus on a living tree would indicate that the tree is rotting internally where the fungus is growing.