Scientific name: Hapalopilus nidulans (Fr.) P. Karst.
Derivation of name: Hapalopilus means "with a soft tender
pileus or cap"; nidulans means "nesting or lying in a cavity."
Synonymy: Polyporus nidulans Fr.
Common names: Tender nesting polypore.
Occurrence on wood substrate: Saprobic; solitary, grouped,
or in overlapping clusters on decaying deciduous (rarely
conifer) wood; June through November.
Dimensions: Caps up to 12 cm wide and 2.5 cm thick.
Upper surface: Brownish-orange to cinnamon-brown; with
matted hairs, becoming glabrous; one or more concentric
Pore surface: Yellowish to cinnamon-brown; 2-4 pores per
Comments: All parts turn purple with KOH.
More information at MushroomExpert.com:
Figure 1. Sessile brackets of Hapalopilus nidulans. These
brackets are soft and watery when fresh. Photo © John
Figure 2. Top and bottom surfaces of tender nesting
polypore. Photo © John Plischke III.
Figure 3. Pore surface of tender nesting polypore.
Photo © Tom Volk.
Figure 4. Enlarged view of the pore surface visible in
Figure 2. Photo © John Plischke III.
Figure 5. The purple discoloration on the cap is from the
application of KOH. Photo © Tom Volk.
Figure 6. Application of ammonia or KOH to the pore surface
produces a purple coloration. Photo © Gary Emberger.