This feature deals with characteristics of the surface of the pileus itself, rather than any coverings such as hairs or scales, for which see Pileus surface (hairs or scales). Some of the features, such as cracking, are more pronounced on older fruit-bodies, but do not record this feature from over-mature specimens (where the pileus has started to shrivel or decay).

Choose this state if: there are ridges or wrinkles on the pileus surface which are often more or less radial, and branching like a river (rivulose). Other terms for this state are rugose or corrugate (when the wrinkles are coarse). If the wrinkles form a network, see wrinkled-reticulate.