Description: Now extinct in Ireland this lichen with orange discs should be seriously searched for. Nicknamed the ‘Orange-fruited elm lichen’, C. lutealba has a thin, grey-white thallus bearing closely grouped orange discs, all in various stages of maturity and development. It was once common on wound tracks on trees. Last reported from an elm growing in County Kildare in 1988 it has since become extinct, the tree having died. It was previously known from a number of the midland and southern counties. C. luteoalba will also grow on horse chestnut, sycamore and maple as well as elm. We could learn a great deal about the species if we could relocate a living population. There is a similar lichen C. ulcerosa which also grows on these trees, but has tiny orange discs that are less profusely produced and minute, blister-like soralia.

Key Identification Features:

• Attractive crustose lichen with profusely produced, small orange discs against a thin, grey-white, cracked thallus
• Often grows on wounded bark where the trunk may have been damaged by machinery.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Cerothallia luteoalba at iNaturalist World Species Observations database.