Observe this feature on the faces of mature lamellae that are shedding spores. Mottling is best viewed either by removing a whole lamella, or by making a longitudinal cross section of the fruit-body, which will expose the faces of two lamellae.

Mottling is due either to synchronous maturation of dark-spored fungi or, occasionally, to pigmented spots on otherwise pale lamellae. Synchronous maturation of spores occurs within small, localised patches on the face of the lamella, with different patches maturing at different times. This fascinating phenomenon is described and illustrated in exquisite detail by Buller (Researches on Fungi, Volume II, Chapters X to XII, 1922).

Choose this state if: the lamellae faces do not appear uniformly mottled. In older fruit-bodies with brown to black spores there is often some spore deposit visible on the lamellae, especially near the edge, or where lamellae are not strictly vertical, but the patches or spots caused by this are localised.