Verrucaria nigrescens (images of British lichens)

Thallus cracked-areolate, dark brown to black, greener when wet, prothallus black, extending under the areoles (section); perithecia small, projecting little above the surfaces of the areoles. Widespread and often common on calcareous rocks, mortar, cement and stonework, including limestone memorials and gravestones.

Refs: Smith et al. (2009), 953; Purvis et al. (1992), 639; Orange (2008); Dobson (2005), 456-7 (photo); Dobson (2011), 464 (photo); van Herk & Aptroot (2004), 386-7 (photo); Wirth et al. (2004), 257 (photo); Thomson (1997), 622, 623 (photo).

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Images of British Lichens