[2] They are characterized by producing fruit bodies (mushrooms) with umbonate caps and rough brown spores.

[3] They are known for a long stipe which continues down into the ground, known as a rooting stipe or pseudorhiza formed as the fruitbody grows up from the subterranean colonized roots well below the organic soil layer.

[4] Molecular phylogenetic work during the 2000s suggests a close relationship to Galerina.

Phaeocollybia is defined as mushrooms, with a glutinous or moist or sometimes dry and innately scaly, conic, umbonate cap, a rooting, cartilaginous to wiry stipe, generally lacking a visible veil or cortina or with faint traces, and spores which are brown in deposit.

The most distinctive feature microscopically is the presence of tibiiform[6] cystidia or branches on the mycelium and mycorrhizal sheaths.