A basidiocarp, basidiome or basidioma (plural: basidiomata), is the sporocarp of a basidiomycete, the multi-cellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures. As with other sporocarps, epigeous (above-ground) basidiocarps that are visible to the naked eye (especially those with a more or less agaricoid morphology) are commonly referred to as mushrooms, while hypogeous (underground) basidiocarps are usually called false truffles.
All basidiocarps serve as the structure on which the hymenium is produced. Basidia are found on the surface of the hymenium, and the basidia ultimately produce spores. In its simplest form, a basidiocarp consists of an undifferentiated fruiting structure with a hymenium on the surface; such a structure is characteristic of many simple jelly and club fungi. In more complex basidiocarps, there is differentiation into a stipe, a pileus, and/or various types of hymenophores.
- Amanita muscaria 3 vliegenzwammen op rij.jpg
Basidiocarps of Amanita muscaria, an agaric.
- Ramaria rugosa var cinerea.jpg
Basidiocarps of Ramaria rugosa, a coral fungus]]
- Cantharellus tubiformis 050920w.jpg
Basidiocarps of Craterellus tubaeformis, a cantharelloid fungus.
Basidiocarps are classified into various types of growth forms based on the degree of differentiation into a stipe, pileus, and hymenophore, as well as the type of hymenophore, if present.
Growth forms include:
- jelly fungus – fruiting body is an undifferentiated mass of jelly-like tissue.
- club fungus and coral fungus – erect fruiting body without a distinct stipe and pileus, either unbranched (club fungus) or profusely branched (coral fungus).
- polypore – fruiting body is hard, woody, and perennial, and often grows shelf-like on the side of a tree or log. Polypores have a pileus, and usually (but not always) tubes and no stipe.
- cantharelloid fungus – fruiting body with shallow fold-like lamellae running over most of the lower surface of the fruiting body and not much differentiation between the stipe and pileus.
- tooth fungus or "hydnoid fungus" – fruiting body with tooth-like hymenophores.
- gasteromycete or "gastroid fungus" – fruiting body has a ball-like shape and in which the hymenophore has become entirely enclosed on the inside of the fruiting body.
- false truffle – like a gasteromycete, however, but with a hypogeous (underground) fruiting body.
- secotioid fungus – like a gasteromycete, but with stipe. Though to be an evolutionarily intermediate stage between a gasteromycete and an agaric.
- agaric or "agaricoid fungus" – fruiting body with a pileus, lamellae, and (usually) a stipe.
- bolete – fruiting body with a pileus, a stipe, and tubes.
Basic divisions of Hymenomycotina were formerly based entirely upon the growth form of the mushroom. Molecular phylogenetic investigation (as well as supporting evidence from micromorphology and chemotaxonomy) has since demonstrated that similar types of basidiomycete growth form are often examples of convergent evolution and do not always reflect a close relationship between different groups of fungi. For example, agarics have arisen independently in the Agaricales, the Boletales, the Russulales, and other groups, while secotioid fungi and false truffles have arisen independently many times just within the Agaricales. 
- Evolution & Morphology in the Homobasidiomycetes: The Clade/Morphology Chart by Gary Lincoff & Michael Wood, MykoWeb, November 27, 2005.
- "Mycomorphology Part 1: Why Do Mushrooms Look Like Mushrooms?" by Peter Werner, Mycena News, December 2002. (Archived at MycoWeb)
- "Mycomorphology Part 2: Basidiocarp Keeps its Balance" by Peter Werner, Mycena News, March 2003. (Archived at MycoWeb)