#143: Boletinellus merulioides, the Ash Tree Bolete
Boletinellus merulioides is an odd mushroom, both in appearance and ecology. The Ash Tree Bolete can be readily identified by its tube surface – which is only a few millimeters thick and looks more like a network of ridges – and by the fact that it fruits under only ash trees. B. merulioides appears under ash because it has a unique symbiotic relationship with a pest of ash trees: the Leafcurl Ash Aphid.