Collema crispum

Small thallus of greenish brown to black overlapping lobes, slightly swollen when moist. Lobe margins may be ascending, wavy, entire or crenate, never swollen.

On damp, calcareous substrates; walls, crumbling mortar, rocks.

All year round.

Most records seem to come from the southern half of Britain.

Status in Leicestershire and Rutland not known.