Major Groups > Cup Fungi / Crust Fungi > Aleurodiscus oakesii


Aleurodiscus oakesii

[ Basidiomycetes > Russulales > Stereaceae > Aleurodiscus . . . ]

by Michael Kuo

If your vision is as bad as mine, it's easier to see Aleurodiscus oakesii, which measures only a few millimeters across, from 20 feet away; it creates smooth patches in the bark of hardwood trees--especially the bark of oaks. In fact, when I wrote this site's page for white oak three years ago, I provided a description and illustration of such a smooth patch, not knowing that the cause was a mushroom!

Up close and personal, Aleurodiscus oakesii requires removing one's glasses (for me, anyway) and pressing one's forehead against the tree to inspect the patches of smooth bark. The tiny, saucer-shaped mushrooms are pale brown, and often appear near the borders of the smooth patches. They are so tiny that there is almost nothing to describe--unless you use a microscope to see the many fascinating and beautiful microscopic features (see the description below).

While Aleurodiscus oakesii is a parasite, it sticks to the outer bark of the trees it infests, and does not seriously threaten the health of its hosts.


Ecology: Parasitic; growing alone or, more commonly, gregariously on the outer bark of hardwoods--especially oaks, elms, and hop hornbeam; appearing year-round, when weather is warm; widely distributed in eastern North America.

Fruiting Body: Only a few millimeters across (to about 5 mm maximum); saucer-shaped or irregular; broadly but centrally attached to the bark; leathery; upper surface pale brown and fairly smooth; under surface whitish and minutely fuzzy; the margin often folded slightly upwards to expose the under surface; without a stem.

Microscopic Features: Spores 17-25 x 12-14 µ; elliptical or egg-shaped; roughened at maturity; amyloid. Acanthohyphidia present, developing prominent and numerous spines. Pseudocystidia present.

REFERENCES: (Berkeley & Curtis, 1873) Patouillard, 1875. (Saccardo, 1888; Lemke, 1964; Chamuris, 1988; Lincoff, 1992; McNeil, 2006.) Herb. Kuo 10270405, 04130601.

This site contains no information about the edibility or toxicity of mushrooms.


Aleurodiscus oakesii

Aleurodiscus oakesii

Aleurodiscus oakesii

Aleurodiscus oakesii

Aleurodiscus oakesii

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2006, May). Aleurodiscus oakesii. Retrieved from the MushroomExpert.Com Web site: