Caloplaca flavocitrina (images of British lichens)

Forming an areolate crust and closely similar to C. citrina, differing in the areoles typically being more greenish yellow, with bright yellow soredia forming initially at the areole margins (though later covering the surface as in C. citrina); apothecia with margins not or hardly sorediate. Widespread and evidently at least locally common, though not generally separated from C. citrina until recently; on base-rich rocks, mortared walls, concrete and on base-rich bark.

Refs: Arup (2006) (photo); Smith et al. (2009), 262; Dobson (2005), 102 (photo); Dobson (2011), 111 (photo, poorly printed); van Herk & Aptroot (2004), 96-97 (photo).

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Images of British Lichens