On calcareous rocks and stones, usually in dry, sunny and very nitrophilous conditions, rarely corticolous, mainly at the dusty base of trees, present in polluted areas (incl. in cities).

Belgium: AC-C.

Luxembourg: AC-C.

France: AC-C.

Lit.: Di: 75-76, Ma: 195-198, 204-207 (p.p.), VGH: 114, Zwaenepoel et al. (1994: 37).