Description: This green-black, rosette-forming ‘jelly lichen’ disintegrates when old, leaving semi-circular ‘moons’ of thallus still attached to the rock; this can be a useful character. When dry it looks like a small, compact, crispy seaweed but is more like a slice through a cauliflower when wet, when the lobes are at their most convoluted. Occasional wart-like isidia are present. Discs are common (to 5mm diam.). It grows on hard limestones; also on mortar and tombs in old churchyards. It is common in Ireland.

Key Identification Features:

• Jelly lichen, crisped when dry, wrinkled and convoluted when wet, discs common
• Easily disintegrating when dry (centres fall out) to leave arcs of thallus.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Lathagrium cristatum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Lathagrium cristatum at iNaturalist World Species Observations database.