Description: Also called ‘rock tripe’ this is a very local species of nutrient-enriched, acid rock outcrops where it can form tremendous colonies. The circular, beige to dark brown thallus is anchored at its centre and is covered in large, pustule-like swellings, resembling a piece of oven-cooked Naan bread. In well-grown specimens the frayed edges become covered in near-black clusters of coralloid isidia. The medulla if tested is C+ red. Western and south-western Ireland. Extreme southern Ireland, thinly scattered elsewhere.

Key Identification Features:

• Unmistakable, pale brown, circular thalli bubbled with pustules and edged with black clusters of coral-like isidia
• On nutrient-rich acid rocks (for example, granites).

Original text submitted by Vince J. Giavarini

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

iNaturalist: Lasallia pustulata at iNaturalist World Species Observations database.