Description: This chalky-white, crustose epiphyte forms extensive, thick, powdery patches towards the base of large, mature trees. Sometimes it can give the impression that the trees have been whitewashed. It is virtually unmistakable; it contains Trentepohlia as the algal partner, so will scratch golden with a fingernail. A dab of Potassium hydroxide (K) turns it pale-lemon yellow. It is relatively common in suitable habitats throughout Ireland.

Key Identification Features:

• The massive, chalk-white stains on trees, golden scratch test, and K reaction will distinguish it
• Mature, well-grown trees are favoured, for example, former parklands, golf courses, etc.

Original text submitted by Simon Davey

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

iNaturalist: Sporodophoron cretaceum at iNaturalist World Species Observations database.