365 Urban Species. #244: Ash Tree Bolete

[urbpan]

Photos by cottonmanifesto. Location: Parkway Road, Brookline. The mushroom on the center right has been turned upside-down, showing the spore-producing underside.

Urban species #244: Ash tree bolete Gyrodon merulioides

A bolete is a mushroom that has a porous spore-bearing surface, rather than the more familiar "gills" (for an example of a gilled mushroom see the amethyst deceiver). The pores of the ash tree bolete are uniquely and rather beautifully shaped. The top of the mushroom looks rather like a carelessly poured pancake, irregularly kidney-shaped, resting on an off-center stalk. The fungus that produces this mushroom always grows in association with the roots of ash trees including green ash, Fraxinus pennsylvanica, a very common urban tree. According to one study* this fungus is dependent on an aphid which feeds on the ash tree, providing nourishment for the fungus as a by-product. Despite this very specific collection of organisms that need to be present for this mushroom to appear, it is not uncommon. Ash tree bolete is edible, despite the fact that it violates an old mushroomer's rule: when bruised, it's flesh stains blue; supposedly an indication that it is poisonous. However, it is not a very well sought-after mushroom, except by slugs and other invertebrate grazers.



* The connection between Gyrodon merulioides and wooly ash aphids was apparently made in a 1987 paper by M.C. Brundrett and B. Kendrick, in the journal Symbiosis. I have found numerous sources using this paper as a reference, but this seems to be the only study describing this relationship. I have not read this paper.