The December 2010 Mushroom of the Month was...
Pleurocybella porrigens (a.k.a. Angel Wings)
In most of our guidebooks, angel wings are listed as an edible mushroom. Several of the books consider angel wings to be a good edible mushroom while others find them bland. I agree with the latter judgment. Although many mycophagists (mushroom eaters), including myself, have eaten these smaller, thin-fleshed relatives of the oyster mushroom for years, currently mycologists recommend not eating them. There was an incident in Japan several years ago where this mushroom caused some deaths. All of the persons who had problems with angel wings already had a compromised renal system. These mushrooms are not a good enough edible to risk problems and we recommend no longer consuming them.
The pure white, thin-fleshed cap of the angel wings is fan-shaped to tongue shaped. It is attached laterally to decaying conifer logs especially to hemlock logs. The look-alike oyster mushroom (Pleurotus ostreatus, our Mushroom of the Month for June 2009) is a larger, much fleshier mushroom ranging in color from an almost pure white to grayish brown to dark brown. Oysters, occurring in large clusters on stumps, logs and trunks of hardwoods, often have thick rudimentary stems whereas angel wings are stemless and are laterally attached to the conifer log they are decaying. The spore print of the angel wings is white whereas the spore print of oysters is lilac (though often very light lilac, almost white). Both mushrooms have pleasant odors and tastes. The pure white caps of angel wings will turn to a somewhat creamy color with age whereas oysters will yellow with age. The cap of the angel wings ranges from 1 to 4 inches wide, oysters range from 2 to 8 inches wide.
Angel wings have had several synonyms: Pleurotus porrigens and Pleurotellus porrigens, which indicate its similarity to the oyster Pleurotus ostreatus even having been placed in the same genus at one time.