Hymenium

The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia (basidiomycetes) or paraphyses (ascomycetes). Cystidia are often important for microscopic identification. The subhymenium consists of the supportive hyphae from which the cells of the hymenium grow, beneath which is the hymenophoral trama, the hyphae that make up the mass of the hymenophore.

The position of the hymenium is traditionally the first characteristic used in the classification and identification of mushrooms. Below are some examples of the diverse types which exist among the macroscopic Basidiomycota and Ascomycota.

Gills of the Fly Agaric Amanita muscaria

The bolete Slippery Jack (Suillus luteus) with bright yellow pores

Giant Puffball Calvatia gigantea

A Stinkhorn, Phallus impudicus

The cup fungus Sarcoscypha austriaca

The large angular pores of Polyporus alveolaris, the hexagonal-pored polypore

...
Wikipedia