Smooth

Anatomy and distribution of the smooth hymenophore

A smooth hymenophore is the simplest type of spore-bearing structure, in which the hymenium (the layer of cells that produces spores) lies on a flat or slightly wavy surface of the fruiting body, without forming complex architecture such as gills, spines or tubes. In "Mushrooms Demystified", David Arora notes that this structure is primitive from an evolutionary point of view, since it doesn't maximize the spore-bearing area as efficiently as gills do.

The lack of pronounced relief is typical of several large ecological and morphological groups of fungi. In her "Handbook of the Fungi of Ukraine", M.Ya. Zerova describes the smooth hymenophore as a characteristic feature of the Clavariaceae — fungi that look like corals or clubs, where spores form directly on the surface of upright branches. This feature is also key for many wood-decaying fungi, especially in the family Corticiaceae, which look like thin films or crusts on wood.

In his guide "Mushrooms", Roger Phillips pays special attention to the fact that a "smooth" hymenophore is often a relative concept. For example, in the famous edible Craterellus cornucopioides, also known as the "black chanterelle" or "horn of plenty", the outer spore-bearing surface is completely smooth at first, but with age or as it dries it may become slightly wrinkled. Even so, true gills or ridges like those of true chanterelles (Cantharellus) never form there.

For a forager, recognizing a smooth hymenophore is usually not difficult, since the surface is visibly and tangibly free of structural elements. Most mushrooms with this hymenophore have a tough, leathery or woody texture and are inedible, although none of them are deadly poisonous species comparable in toxicity to the death cap.