Bondarzewia berkeleyi

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Bondarzewia berkeleyi, commonly called Berkeley's polypore or stump blossoms, is a polypore fungus that parasitizes oaks and other hardwoods, causing butt rot. It is found widely in Europe, Asia, Africa, and North America east of the Great Plains, with fruiting mainly from July to October in the United States.

Description
The fungus forms fan- or shelf-shaped caps that grow in overlapping clusters at the bases of trees, each cap about 20–50 cm across. Colors range from white to pale grey, cream, beige, or yellow, with a white pore surface underneath. The spore print is white. Spores are round, 7–9 by 6–8 μm, with amyloid ridges. The flesh is white and up to about 3 cm thick, usually mild in taste when young and turning bitter with age; the outer edges are tender.

Habitat and host
The primary host is oak, but it can grow on other hardwoods such as maple. In North Carolina, it was found mainly on various oaks (white, scarlet, southern red, chestnut, eastern black) and occasionally on bird cherry. The fruiting bodies appear on infected trees in summer and fall. The fungus causes butt rot in the lower trunk and heartwood, typically not rising more than about 0.9–1.5 m, and the decay is often white and stringy.

Ecology
Bondarzewia berkeleyi is primarily parasitic but can act as a saprophyte on dead trees or stumps.

Edibility
Young specimens are sometimes eaten if well cooked, but older fruit bodies become tough and bitter and may cause stomach upset or allergies in some people. Some people use it as a meat substitute or to enhance flavor after parboiling or blanching to remove bitterness.