On exposed and nitrophilous bark, mainly on trees along roads and in orchards, rarely lignicolous, also saxicolous, especially on concrete and asbestos.

Belgium: Mar.: CC, Fl.: CC, elsewhere: AC-CC.

Luxembourg: Ard.: AC, Lorr.: C.

France: Mar.: AR, Boul.: AR, Pic.: R, Mosan, Ard., Lorr.: C.

Lit.: Boul.: 72, Ca: 157-158, Ho: 206, La66: 471-472, Qu: 117-119, WS: 46-47, 93.