Cap: Pileus color ranges from whitish, to yellowish to brown. Individually, caps are convex to flat and can reach 25 cm. Their outline is kidney to fan shaped, and feels leathery to the touch (Kuo 2004). Margin may be wrinkled. Concentric zonation exists to varying degrees. Flesh reaches 3 cm thick and gets tough with age, unbruising. When fresh, a small amount of latex can sometimes be observed when the flesh is broken.
Spore bearing surface: Cream colored, with angular, decurrent pores. Pores are often irregular, 0.5-2 per mm (Bessette 1997). Pore length reaches 1 cm.
Stalk: Rough, sturdy, yellow to brown, can be 10 cm tall and 3-5 cm wide.
Spores: White, ornamented (spines), amyloid and globose to subglobose. They are born on basidia and range from 6-9 µm across. The spores look much more like those of a Russula than a typical polypore.
Hyphal structure is dimitic skeletal. Hyphae are inamyloid and sphaerocysts are not present (Miller et al. 2006).