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Pleurotus populinus: The Aspen Oyster
by Michael Kuo
Pleurotus populinus is part of the oyster mushroom complex, which is centered around the "true" oyster mushroom, Pleurotus ostreatus. I call Pleurotus populinus the "aspen oyster," since it appears to be limited to the wood of quaking aspen and closely related trees (aspens and cottonwoods in the genus Populus). It is northern and montane, corresponding to the range of the host trees. It is a well established biological species (meaning that it cannot "mate" with the other oysters) supported by DNA evidence. Fortunately for those of us who do not have mycology laboratories at our disposal, its ecology (the relationship to aspen) and even a few morphological features are distinct. The cap is not dark brown, as it sometimes is in Pleurotus ostreatus, and the spore print is always whitish rather than whitish to grayish or lilac. Under the microscope it has longer spores than Pleurotus ostreatus or Pleurotus pulmonarius.
Ecology: Saprobic; growing in shelf-like clusters on dead and living wood of Populus species, primarily quaking aspen; causing a white rot; spring, summer, and fall; widely distributed in northern and montane North America, throughout the range of the host trees.
Cap: 2-15 cm; convex, becoming flat or somewhat depressed; kidney-shaped to fan-shaped, or nearly circular if growing on the tops of logs; somewhat greasy when young and fresh; smooth; whitish to pinkish gray or pale tan, without dark brown colorations; the margin inrolled when young, later wavy.
Gills: Running down the stem; close or nearly distant; whitish.
Stem: Usually absent or rudimentary, when the mushroom is growing from the side of a log or tree. When it grows on the tops of logs or branches, or at an angle, however, it may develop a substantial and thick stem that is dry and slightly hairy near the base.
Flesh: Thick; white.
Odor and Taste: Odor distinctive but hard to describe; taste mild.
Chemical Reactions: KOH on cap surface negative to yellowish.
Spore Print: Whitish (never lilac).
Microscopic Features: Spores 9-12 x 3-5 µ; smooth; cylindric to long-elliptical. Compare with measurements for the epitype collection of Pleurotus ostreatus, rather than measurements quoted in most field guides.
Further Online Information:
Pleurotus populinus at Univ. Tennessee
Cite this page as:
Kuo, M. (2006, August). Pleurotus populinus: The aspen oyster. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/pleurotus_populinus.html