Lecanora muralis (images of British lichens)

Thallus placodioid (a crust with a lobed, almost foliose margin), pale- to brownish cream, greenish-grey or grey; apothecia with yellow- to grey- or red-brown discs, often crowded and becoming angular. On natural, bird-enriched rocks, and on concrete and other urban substrates; widespread and becoming very common in urban areas, less so in the north and west. On paving slabs often assumed to be discarded and trodden chewing gum – see lower photographs (compare Aspicilia contorta).

Refs: Smith et al. (2009), 491; Purvis et al. (1992), 309; Dobson (2005), 211-212 (photo); Dobson (2011), 217 (photo); Jahns (1983), 206-7 (photo); van Herk & Aptroot (2004), 214-215 (photo); Wirth (1995), 1: 452-453 (photo); Wirth et al. (2004), 189 (photo); Moberg & Holmåson (1984), 117 (photo); Holien & Tønsberg (2008), 184 (photo, as Protoparmeliopsis muralis); Fox et al. (2003), plate 8 (photo); Hansen & Anderson (1995), 95 (photo); Puntillo (1996), plate 22 (photo); Brodo et al. (2001), 383 (photo); Thomson (1997), 295, 296 (photo).

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Images of British Lichens