In shaded and sheltered underhangs of calcareous or siliceous rock, on walls, also in deep crevices at the base of trunks, on exposed roots of trees and on Quercus in old forests, often by rivers at water level.

Belgium: Mosan: RR, Ard.: R.

Luxembourg: Ard.: RR, Lorr.: RRR.

France: Ard.: RRR.

Lit.: NL97: 17, Kuborn & Diederich (2008).