Phlyctidaceae Phlyctis argena Growth type crustose Chemical results: K+ yellow turning red, C-, KC+ red, P+ orange-red, UV- Usually on well-lit deciduous trees, rare on conifers, occasional on shaded, +/- basic rocks and walls. Pale grey-green or whitish thallus with paler prothallus. White to greenish soredia, sparse or abundant and +/- covering thallus centre. Apothecia are rare, the pruinose discs greyish-black with thin margins. Host to Opegrapha zwackhii; spores 3-4(-5) septate, 18-24 x 6-8 µm Similar: Phlyctis agelaea. Apothecia frequent, soredia absent. Ochrolechia subviridis is K-, C+ orange > red

Phlyctis argena
On Oak. Holton Lee, Dorset. December 2012