The hyphal system of the pileus trama is the number of types of hyphae: one type in a monomitic trama, two types in a dimitic trama and three types in a trimitic trama.

To establish the hyphal system, take a small piece of pileus trama tissue and mount in KOH to facilitate separation of the individual hyphae. Use needles to tease apart the hyphae before adding a cover slip and applying gentle pressure to spread apart the hyphae. Mature specimens should be examined, since young material can be monomitic, but later become dimitic as skeletal hyphae develop (as in Pleurotus djamor).

Generative hyphae are always present, and are septate and often with clamp connections. In a dimitic trama, skeletal hyphae (or rarely skeleto-ligative hyphae) are also present, along with generative hyphae. In a dimitic trama, the skeletal hyphae may be very common, and make finding generative hyphae difficult. In a trimitic trama there are generative, skeletal and binding hyphae.

Choose this state if: the hyphae of the context are of two types (dimitic) or three types (trimitic).

In the dimitic trama there are generative hyphae (which are typically thin-walled, although not always, and septate, often with clamp connections) and skeletal hyphae (which are thick-walled and aseptate without clamp connections, although they may be clamped at the base). The wall of skeletal hyphae may be so thick as to obscure the lumen. Skeletal hyphae are intercalary or terminal, as much as 1500 micrometres long, and typically unbranched and without a tapering apex, but can be branched (in skeleto-ligative hyphae) [see Pileus trama (secondary hyphae)]. We also accept as skeletal hyphae thick-walled terminal elements that have a tapered apex, such as can occur in Pleurotus. These are sometimes referred to as sclerified generative elements.

In a trimitic trama there are generative, skeletal and binding hyphae. Binding hyphae are thick-walled and highly branched. When there is a long unbranched basal portion, the term 'arboriform skeletal hyphae' is sometimes applied; we include these under binding hyphae.