[1] The genus was circumscribed in 1985 to contain the species originally described as Agaricus lignatilis by Christian Hendrik Persoon in 1801.

[2] This was considered the sole species in the genus until 2007, when Marco Contu validly published a description of O. lachnopus from collections in Italy.

[4] Molecular genetics analysis suggests that Ossicaulis is most closely related to the genera Asterophora, Hypsizygus, Lyophyllum, and Tricholomella.

[5] Ossicaulis species have gills that are adnexed, adnate or somewhat decurrent and a stipe that is centrally or laterally attached to the cap.

Both species grow on dead and decaying wood of deciduous (rarely coniferous) trees.