The Paxillaceae are a family

Family

In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...

 of mushroom

Mushroom

A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

s bearing close affinity to the Boletes

Boletaceae

Boletaceae are a family of mushrooms, primarily characterized by developing their spores in small pores on the underside of the mushroom, instead of gills, as are found in agarics. Nearly as widely distributed as agarics, they include the Cep or King Bolete , much sought after by mushroom hunters...

. Collectively, the family contains nine genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 and 78 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. The type genus

Type genus

In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...

 is Paxillus

Paxillus

Paxillus is a genus of mushrooms of which most are known to be poisonous or inedible. The widespread genus contains 15 species. Species include Paxillus involutus and Paxillus vernalis...

, containing fungi with decurrent gills, and Gyrodon

Gyrodon

Gyrodon is a genus of pored mushroom bearing close affinity to the genus Paxillus. Recent molecular research has confirmed this relationship of the two genera as sister groups, together lying near the base of a phylogenetic tree from which the genus Boletus arises.Species include Gyrodon lividus of...

, which has members with decurrent pores, among others. French mycologist René Maire

René Maire

René Charles Joseph Ernest Maire was a French botanist and mycologist. His major work was the Flore de l'Afrique du Nord in 16 volumes published posthumously in 1953. He collected plants from Algeria, Morocco, France, and Mali for the herbarium of the National Botanic Garden of Belgium.- Biography...

 had erected the family in 1902, placing it between the agarics and boletes and recognizing the groups' similarities with the latter group. More recent molecular research confirms the relations of Gyrodon, with the decurrent-pored mushroom G. lividus

Gyrodon lividus

Gyrodon lividus, commonly known as the alder bolete, is a pored mushroom bearing close affinity to the genus Paxillus. It is also known as Uloporus lividus by some authorities. Found predominantly in Europe, though also recorded from Japan and California, it is distinguished by its decurrent...

, and Paxillus as sister groups, together lying near the base of a phylogenetic tree

Phylogenetic tree

A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...

 from which the genus Boletus

Boletus

Boletus is a genus of mushroom, comprising over 100 species. The genus Boletus was originally broadly defined and described by Elias Magnus Fries in 1821, essentially containing all fungi with pores...

arises.