Order: Arthoniales       Family: Roccellaceae Species: Opegrapha herbarum Growth type crustose. Photos: Ardnagashel and Macroom, Co.Cork, Ireland. Identified by Andy Acton and John Douglass Thin or inconspicuous pale grey, brownish or olive-green thallus.The small, scattered lirellae are usually simple, less frequently branched. Slit-like discs becoming fully open, occasionally +/- green-pruinose. Pycnidia are very rare. Asci are 8-spored, spores 3-septate, 18-25 x 5-8 µm with thin perispore. Microscope photographs below. Occurs on acid to basic, smooth, often shady bark. Also found on plant stems (especially brambles) and sandstone. Chemical reactions negative.

Microscope photographs




Opegrapha herbarum March and May 2010