A much-branched perennial herb growing from the cracks and mortar crevices of brick and stone walls, on building rubble, rocks, cliffs and steep-sided hedge banks. It prefers dry, sunny, sheltered spots, and is often found in built-up areas or not far from habitation. Lowland.
There appears to have been little change in distribution since the 1962 Atlas, where it was mapped as `all records`. Its frequent occurrence on the walls of abbeys and priories is possibly connected to its use by medieval herbalists as a remedy for urinary disorders.
Submediterranean-Subatlantic element; also in C. Asia.