See text Rhizocarpon is a genus of crustose, saxicolous (or sometimes lichenicolous), lecideoid lichens in the family Rhizocarpaceae.

Together with three small genera (Catolechia, Poeltinula and Epilichen), Rhizocarpon constitutes the family Rhizocarpaceae.

[9][10][11] [12] In molecular work, the genus has also been shown to be paraphyletic, with closely related genera being nested within Rhizocarpon.

The genus has a distinct type of ascus, the Rhizocarpon-type,[14] which is bitunicate with the inner ascus-wall being slightly apically thickened.

They are either 2-celled (1-septate) or multi-celled (muriform) and are either hyaline or pigmented (green or brown), often with a characteristic halo (perispore) visible when viewed in a microscope.