 The spore surface is warty and full of wrinkles, with a smooth depression where the spore was once attached via the sterigmatum to the basidium (the spore-bearing cell).When in potassium hydroxide (KOH) solution, the spores appear tawny or darker rusty-brown, with an apical callus.The basidia are four-spored (rarely with a very few two-spored ones), roughly cylindrical when producing spores, but with a slightly tapered base, and measure 21–29 by 5–8.4 µm.