Crepidotus applanatus
Description
Crepidotus applanatus is a species of fungi in the family Crepidotaceae. It is a tiny, kidney-shaped fungus that appears on dead wood of deciduous broadleaf trees. The attachment is sessile (having no stem).
Uncommon but quite widely distributed in woodlands throughout mainland Europe and is also recorded in many other parts of the world including North America.
These small, stalkless, white mushrooms are sometimes mistaken for small oyster mushrooms, Pleurotus ostreatus. Crepidotus species have brown spore prints whereas oysters have white to lilac spore prints.
Common names: Flat Crep.
Mushroom Identification
Ecology
Saprobic; growing gregariously or (more commonly) in overlapping clusters on dead hardwood stumps and logs; summer and fall; widely distributed in North America.
Cap
1-4 cm; shell-shaped or petal-shaped; somewhat flabby; smooth or finely velvety (towards the point of attachment) in all stages of development; the margin often slightly lined; white, becoming brownish to pale cinnamon-brown; hygrophanous.
Gills
Close or crowded; whitish, becoming brownish in maturity.
Stem
Absent. Rarely, when conditions force the mushroom to grow straight upwards rather than in a shelf-like position, the cap may be nearly circular, creating the illusion of a rudimentary "stem" where the mushroom attaches to the wood.
Flesh
Soft; thin.
Odor and Taste
Odor not distinctive; taste mild.
Spore Print
Brown.
Microscopic Features
Spores 4-6 µ; globose; very finely punctate or roughened (often hard to discern even with oil immersion). Pleurocystidia absent. Cheilocystidia variously shaped; up to 50 x 12 µ. Pileipellis a cutis with occasional erect elements. Clamp connections are present.
Look-Alikes
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Has a scalloped margin.
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Has a transparent cuticle layer that is evident when the cap is stretched.
History
The Flat Oysterling was described in 1796 by Christiaan Hendrik Persoon, who established its basionym when he gave it the binomial scientific name Agaricus applanatus. It was German mycologist Paul Kummer who, in 1871, transferred this species to the genus Crepidotus, whereupon it acquired its currently accepted scientific name Crepidotus applanatus.
Synonyms of Crepidotus applanatus include Agaricus applanatus Pers., Agaricus putrigenus Berk. & M.A. Curtis, and Crepidopus putrigenus (Berk. & M.A. Curtis) Sacc.
The generic name Crepidotus comes from crepid- meaning a base, such as a shoe or a slipper (although some sources state that it means 'cracked'), and otus, meaning an ear - hence it suggests a 'slipper-like ear'.
Photo sources:
Photo 1 - Author: Jerzy Opioła (CC BY-SA 3.0)
Photo 2 - Author: gailhampshire (CC BY-SA 2.0)
Photo 3 - Author: gailhampshire (CC BY-SA 2.0)
Photo 4 - Author: Jerzy Opioła (CC BY-SA 3.0)