Observe the hyphae of the pileus trama (flesh) below the surface layer (pileipellis).

This feature is included so that observations of thick-walled hyphae may be included, without needing to establish the Pileus trama (hyphal system) (whether the trama is monomitic or dimitic). Thick-walled hyphae may be present when the trama is monomitic (all the hyphae are thick-walled) or dimitic (there is a mixture of thin-walled generative hyphae and thick-walled skeletal hyphae).

Choose this state if: at least some of the hyphae of the pileus trama are distinctly thick-walled (walls > 1 micrometre thick). Thick-walled hyphae may be septate or aseptate.

Note that when the hyphal system is dimitic, there is a mixture of thin-walled and thick-walled hyphae.