A late season cousin to the Oyster Mushroom, the
Elm Oyster is a slow growing and very durable mushroom. Typically
fruiting from wounds on boxelder, it can be watched as it slowly grows
over the course of several days. It may take ten days to reach full
growth. It will then begin to develop the characteristic cracks in
the surface. If left undisturbed it could remain on the tree for
While it resembles the common Oyster Mushroom,
it is noted for having a prominent stalk that is off center to nearly central.
Its gills are attached but not decurrent. It has also been known
as Hypsizygus tessulatus, but recent studies by Scott Redhead indicate
this name belongs to a smaller mushroom.