Micarea prasina s.l. Fr.

    Thallus composed of dense goniocysts, 12-18 µm diam., sometimes aggregated to form small granules, green-yellowish, more or less dark green, grey-greenish, becoming emerald green at the end or in herbarium. Apothecia convex to subglobose, sometimes tuberculate, 0.2-0.4 mm diam., at first whitish, then greyish, pale greyish-brown and finally blackish, exciple inconspicuous, often absent. Ascii utriform, 8-spored, 5-60 x 20-25 µm according to our measures. Ascospores colourless, ovoid to oblong, simple, 1-(3)-septate, 8-12 x 3-4 µm according to literature, 10-13 (15) x 4-5,5 µm according to our measures. Photobiont: micareoid. Thallus and apothecia: C-, K-, KC-, Pd-. On stumps, tree trunks in old woodlands, seldom on ground or rocks; see Micarea prasina s.l. forme océanique et Micarea prasina s.l. forme maritime.

N.B. It seems wise to consider Micarea prasina sensu lato since there are at least two other taxa very difficult to distinguish unless a chemical analysis is performed:  Micarea micrococca that would be the most common and Micarea subvirescens which shows maritime trends. These two latter taxa sometimes are considered as chemotypes of Micarea prasina or separate species.