Description: On first sight this large foliose lichen is not dissimilar to Parmotrema perlatum (described elsewhere). However, in P. reticulatum the lobes will be seen to be minutely cracked to form a net of tiny lines across the surface of the cortex. Some lobes are more intricately netted than others. A dusting of soredia is usually present on the ends of the turned-down lobe tips. The medulla (layer below the outer cortex), if exposed, should react K + yellow to red, Pd-. This species is frequent in Ireland, especially on isolated and wayside trees in the low-lying coastal areas and along the principal river valleys further inland.

Key Identification Features:

• It is very similar to Parmotrema perlatum from which it is readily separated by the many distinctive hairline cracks that cross its surface
• The medulla of P. perlatum reacts K + yellowy-orange only; Pd + orange.

Original text submitted by Simon Davey

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

iNaturalist: Parmotrema reticulatum at iNaturalist World Species Observations database.