Opegrapha xerica Roccellaceae
Opegrapha xerica

Growth type crustose.
Chemical results negative. Epithecium brownish in water, K+ olive-green

Found on dry acidic bark, particularly of mature and old Oaks and Yews, and spreading onto nearby Ivy and dead bramble stems.

Thin grey or greenish thallus with (usually) simple lirellae. Disc slit-like becoming +/- expanded, sometimes pruinose. Spores are 3-5 septate, sometimes with a larger middle cell, 14-20 x 4-5.5 Ám.
Microscope photographs below.

Similar: O. varia. Epithecium brown, K-. Larger spores, 4-6 septate


Opegrapha xerica

Opegrapha xerica

Opegrapha xerica

Microscope photographs
Opegrapha xerica

Opegrapha xerica

Opegrapha xerica
Opegrapha xerica
Lytchett Minster and Puddletown, Dorset. December 2016, May 2017

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