A crustose species with a thin to thick thallus that is usually smooth or only slightly cracked. It is white to creamy or greenish grey with a pale prothallus and may cover extensive areas. White to greenish soralia form eroded lines before becoming confluent and covering a large part of the thallus.
Thallus: C-, K+ blood red, UV-
Except from parts of the north and west, Phlyctis argena is widespread in Scotland. It grows on well-lit, nutrient-rich trees. BLS distribution map
scottishlichens.co.uk 