Cladonia uncialis is a species of fruticose, cup lichen in the family Cladoniaceae.

It was first described as a new species by Swedish taxonomist Carl Linnaeus in 1753.

[1] It was transferred to the genus Cladonia by Friedrich Heinrich Wiggers in 1780.

[2] In North America, the lichen is colloquially known as the thorn Cladonia[3] or the thorn cup lichen.

[4] Cladonia uncialis is host to the lichenicolous fungus species Lichenopeltella uncialicola, which is named after C.