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Images of British Lichens

Xanthoria parietina (L.) Th.Fr.

Foliose, pale- to golden-yellow or orange, grey in shade, lacking isidia or soredia; apothecia usually present, margins concolorous with thallus, discs orange. Throughout Britain, generally very common on nutrient-enriched bark (especially on Elder, Sambucus nigra) and stonework, often abundant on coastal rocks (see, also, X. aureola), further increasing as a result of nitrate/ammonia deposition from atmospheric pollution.

Refs: Smith et al. (2009), 970; Purvis et al. (1992), 646; Dobson (2005), 463 (photo); Dobson (2011), 473 (photo); Jahns (1983), 248-249 (photo); Allen (2007), 40 (photo); Dalby & Dalby (2005), 13 (photo); Fox et al. (2003), plate 8 (photo); Whelan (2011), 151 (photo); van Haluwyn et al. (2009), 32-3 (photo); van Herk & Aptroot (2004, 2013), 398-9 (photo); Wirth (1995), 2: 973, 977 (photo); Wirth et al. (2004), 127 (photo); Wirth, Hauck & Schulz (2013), 1: 16 (photo), 2: 1190 (photo), 1192; Frahm et al. (2010), 151 (photo); Moberg & Holmåson (1984), 191 (photo); Holien & Tønsberg (2008), 104 (photo); Stenroos et al. (2011), 41 (photo), 501 (photo), 506 (photo); Valcárcel et al. (2003), 380-1 (photo); Hinds & Hinds (2007), 524 (photo); Brodo et al. (2001), 746, 747 (photo); McCune & Geiser (2009), 397 (photo).

Frequently parasitised by Xanthoriicola physciae. Host also to, e.g., Lichenoconium xanthoriae, Opegrapha physciaria.

Xanthoria parietina, on concrete, Wicken Fen
On concrete, Wicken Fen, Cambridgeshire, April 2007
Xanthoria parietina, on Salix in carr, Wicken Fen
Xanthoria parietina, on Salix in carr, Wicken Fen, close-up
On Grey Sallow (Salix cinerea subsp. cinerea) in dense carr, showing the thallus remaining grey when it receives little sunlight,
Wicken Fen, Cambridgeshire, April 2007
Xanthoria parietina, on concrete coastal wall, Arbroath
On concrete coastal wall, Arbroath, Angus, April 2002
Xanthoria parietina, on Tilia trunk, Paisley, showing purple reaction with KOH
On Lime (Tilia x europaea), showing the instant purple reaction with potassium hydroxide, Paisley, Renfrewshire, April 2008
Xanthoria parietina, on roof, Ely
Xanthoria parietina, on roof, Ely
Colonisation of nutrient-enriched roof gables where birds perch, Ely, Cambridgeshire, March 2006

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© A.J. Silverside
Uploaded August 2008, last modified or updated April 2014 (first hosted at, January 2003, substantially extended)