On calcareous, natural outcrops, and in artificial habitats like on old walls or concrete.

Belgium: Fl.: RRR, Mosan: R, Ard.: RR, Lorr.: RRR.

Luxembourg: Ard.: RRR, Lorr.: R.

France: Mar.: RRR (1947), Brab.: RRR (1948), Lorr.: RR.

Lit.: L5: 23, NL84: 14, NL92: 170, van den Boom (1992: 242-244).