For Mushroom Monday this week we have a beautiful little oyster mushroom. Unfortunately though, this is not the oyster mushroom typically found growing on oaks here, that is prized by foragers. This is the ‘mock oyster’ (Phyllotopsis nidulans). I was excited at first glance as I thought perhaps this was a true oyster mushroom, but on closer inspection, it clearly is not.
Phyllotopsis nidulans is a member of the Tricholomataceae family. The Mock Oyster was once placed in the genus Pleurotus, the true edible oyster mushrooms, and it is a convincing look-alike. Don’t be fooled though, this species may be non-toxic, but Phyllotopsis nidulans is distinctly lacking in culinary value.
The Mock Oyster is distributed widely across North America and Europe, although reportedly somewhat rare in the Pacific Northwest, and can usually be found clustered on decaying hardwoods and conifers from fall to late winter.
Like most fungi found here, the Mock Oyster is an agaric, a gilled mushroom species.
Although similar in shape, it is distinctly different from a true oyster mushroom in its coloration. Even from a distance, the bright apricot-orange color of the cap and gills make this species stand out from the drab greens and browns on the forest floor near the creek.
The spore print of this species is pink. Even though the spores, and flesh, of this mushroom species are brightly colored though, Phyllotopsis nidulans is reportedly of little to no value as a dye.
Some report this species to have a particularly offensive skunk-like odor, but these specimens weren’t particularly aromatic. They were however, otherwise typical of the species.
The caps are stemless, growing up to 8 cm in diameter, and somewhat kidney-shaped.
The fans have inrolled margins when young, and become more plane to convex with age.
Aside from their unique color, the dorsal surface of the fan-shaped caps are noticeably hairy, unlike the true oyster mushrooms. This gave rise to the species name nidulans, which is Latin for ‘nesting’, due to the downy almost nest-like caps.
The first part of our winter was promising for fungi, and we’ve found some interesting species so far, but since late November we’ve been entrenched in the midst of persistent high pressure attributed to our La Niña weather pattern, making fungi few and far between. Unless our rains return soon, Mushroom Mondays for the remainder of the season may find themselves in jeopardy.
On the upside though, it’s another great day to head out to the garden!
 Trudell, S., and Ammirati J. 2009. in Mushrooms of the Pacific Northwest. p. 139. Timber Press.
 Bessette, A. R., and Bessette, A. 2001. in The Rainbow Beneath My Feet: A Mushroom Dyer’s Field Guide. p. 164. Syracuse University Press.