On siliceous, natural outcrops, often on shaded, vertical surfaces or on overhangs.

Belgium: Mosan: RR, Ard.: AR.

Luxembourg: Ard.: AR.

France: Ard.: RR.

Several populations from Ard. (Belgium: and

Luxembourg:) have been examined by TLC and all contain protocetraric acid. Thus, the closely related L. ochroidea (Ach.) Nyl. does not seem to occur in the study area.

Lit.: La69: 104, Mü4: 109, NL84: 15, NL92: 171, NL97: 50.