Caloplaca flavescens (images of British lichens)

Thallus yellow to orange, placodioid (i.e. a crust but lobulate at the margins), often with a whitish zone at the base of the lobules, more obvious in intact thalli (but seen also in related species), lobules convex, generally slightly pruinose; apothecia deeper orange and crowded in the centre of the thallus. Easily confused with C. aurantia, which has more flattened lobules, and with C. decipiens, which is sorediate towards the centre of the thallus. Common, especially in the south and east, on calcareous rocks, walls and cement.

Refs: Gaya (2009), 109, 187 (photo); Smith et al. (2009), 262; Purvis et al. (1992), 151; Dobson (2005), 101-2 (photo); Dobson (2011), 110-11 (photo); Allen (2007), 33 (photo); Wirth (1995), 1: 216, 231 (photo); Wirth et al. (2004), 235 (photo); van Herk & Aptroot (2004), 94-95 (photo); Moberg & Holmåson (1984), 186 (photo, as C. heppiana); Lichen Atlas of the British Isles 6: 259 (2001).

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Images of British Lichens