Lichens of Wales

Parmelinopsis horrescens


Parmelia horrescens

Description & Identification

Usually fairly distinctive on acidic bark and lignum and more rarely on siliceous rocks with its shiny narrow grey-white lobes forming neat rosettes, tight against the substrate and usually covered in black-tipped minute rod-like isidia that seem excessively large for the size of the thallus lobes. It looks like a small Parmelia saxatilis with narrow, divided lobes, somewhat truncate at the tips but with, in addition to the oversized isidia an abundance of black cilia growing out from around the bases of and sometimes the tips of the isidia. On account of this well-developed stubble it might not unreasonably called the “Desperate Dan” lichen. It has a C- medulla in contrast to the C+ pink medulla of Parmelinopsis minarum that also lacks cilia. 

Photo: R G Woods


Unlike many Section 42 lichens this species is most definitely not a member of the “Lobarion” but enjoys smooth acidic bark of trees such as birch, rowan, alder and young oak. It also grows frequently on lignum and occasionally on siliceous rocks. It is a member of the Parmelietum laevigatae that favours damp ravine woodlands in the highest rainfall areas and can often be abundant on quite young trees.

Threats and Status
Hectad Distribution in Wales/Link to NBN Gateway Map

NBN Taxon Key