Rhizocarpon petraeum Rhizocarpaceae
Rhizocarpon petraeum

Growth type crustose
Chemical results: Medulla: K+ yellow, P+ yellow-orange

Found in urban and rural areas on intermediate rocks (slightly-basic to slightly-acidic).

Cracked, areolate thallus, chalky-white with dark prothallus. Irregularly-shaped black apothecia (to 1mm) with paler margins, often arranged in concentric rings. Green-brown epithecium. Spores muriform, colourless becoming dark when old, 20-50 x 13-25 Ám.

Similar: Rhizocarpon reductum


Rhizocarpon petraeum


Rhizocarpon petraeum
Rhizocarpon petraeum
On wall. Westbourne, Dorset. January 2013

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