Phlyctis argena

Phlyctis argena is a species of crustose lichen.

Description

Phlyctis argena has a thin crustose thallus that is white, greyish or green-grey in colour. The identification can be confirmed with the spot test application a drop of potassium hydroxide to the thallus, which will turn yellow and then red.

Range

The species is widespread, including in Africa, Asia, Europe, and North America.

Habitat

Phlyctis argena usually grows as a generalist epiphyte on the bark of deciduous trees, especially Salix cinerea and Fraxinus excelsior.
It also occasionally grows on stone, such as gravestones.

Ecology

The lichen is a generalist epiphyte of deciduous trees and is acidophilic. Its abundance appears to have increased generally since the 1970s, possibly in responses to changes in air pollution levels

Etymology

The etymology of the genus name, Phlyctis, comes from the obsolete medical term phlyctidium, meaning a large blister. The species epithet, argena, is derived from the latin "argentum", meaning silver.

Taxonomy

The following varieties of Phlyctis argena have been described:Phlyctis argena var. argenaPhlyctis argena var. gilvoalbicansPhlyctis argena var. erythrosoraPhlyctis argena var. ''nubilosa''