Pertusaria pertusa (images of British lichens)

Thallus whitish or greenish grey to grey, surface conspicuously warted, each wart with several sunken, dark apothecia with narrow openings like the top of a pepper-pot; microscopically characterised by its mostly 2-spored asci. Throughout the British Isles and often common on tree trunks, less often on rocks and stonework.

Refs: Smith et al. (2009), 685; Purvis et al. (1992), 458; Dobson (2005), 329 (photo); Dobson (2011), 329-30 (photo); Jahns (1983), 254-255 (photo); van Haluwyn et al. (2009), 184-5 (photo); van Herk & Aptroot (2004), 292-3 (photo); Wirth (1995), 2: 698 (photo); Wirth et al. (2004), 279 (photo); Moberg & Holmåson (1984), 210 (photo); Holien & Tønsberg (2008), 179 (photo); Puntillo (1996), plate 30 (photo).

lastdragon.org

Images of British Lichens