Description: This crustose, bark lichen grows most prolifically on hazel, so look for it there. The thallus is pale greenish or a silvery, creamy-yellow when dry, but the giveaway feature is when it occurs in the pycnidial form. Through a lens these tiny spots are black, triangular and pip-shaped, sometimes even barbed like a thorn. Over one hundred would fit comfortably on the head of a nail. On hazel, in humid sheltered woodland, it occurs within mosaics of other species. Northern and western Ireland.

Key Identification Features:

• Hazel specialist bark lichen, small (thallus 1-2cm across), pale, silvery-brown, with numerous dots, many merging
• Dots (pycnidia) black, triangular, barbed, pinprick sized; often growing with Graphis and associated smooth bark lichens.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Celothelium ischnobelum at iNaturalist World Species Observations database.