Staffan Widstrand / Lichen (Xanthoria sp) growing on rocks by coastline, Svalbard, Norway

Adrian Davies / Orange coloured Seashore Lichens (Xanthoria parietina) and Sea Ivory (Ramalina siliquosa) UK, August

Robert Thompson / Lichen (Xanthoria aureola) Ballywhoriskey Point, County Donegal, Northern Ireland. October.

Robert Thompson / Lichen (Xanthoria aureola) Ballywhoriskey Point, County Donegal, Northern Ireland. October.

Chris Mattison / Lichen zonation showing oil-tar lichen, Verrucaria maura (black zone), Caloplaca sp. and Xanthoria sp. (yellow zone) Mull, Scotland

Chris Mattison / Coastal lichen (Xanthoria aureola) Isle of Mull, Scotland, UK, June.

Chris Mattison / Elegant sunburst lichen (Xanthoria elegans) Baguales Valley, Chile.

Chris Mattison / Elegant sunburst lichen (Xanthoria elegans) Baguales Valley, Chile.

Chris Mattison / Yellow sunburst lichen (Xanthoria parietina) growing on a headstone, Fetlar, Shetlands, Scotland, UK, June.

Chris Mattison / Lichen (Xanthoria ucrainica) on headstone, Fetlar, Shetlands, Scotland, UK, June.

Chris Mattison / Colony of lichens on granite rock, including Elegant sunburst lichen (Xanthoria elegans) - orange, Xanthoria candelaria - yellow, Rock posy, (Rhizoplace sp) - grey, and several others. Chile.

Alex Hyde / Common Orange Lichen (Xanthoria parietina) growing on a road sign. This species is very resitant to air pollution.Peak District National Park, Derbshire, UK. April.

Chris Mattison / Yellow Lichen (Xanthoria parietina) Valgrisenche, Italian Alps, Italy, July.

Nick Upton / Circular patch of Common orange lichen (Xanthoria parietina) growing on rocks just above the high tide line, Severn Beach, Somerset, UK, April.

Adrian Davies / Lichens including Xanthoria parietina and Ochrolechia parella on tombstones in village churchyard. Slapton, Devon, England, UK, July 2013.

Chris Mattison / Common orange lichen (Xanthoria parietina) on Hawthorn twig (Crataegus monogyna) together with a Shield lichen (Parmelia sulcata) England, UK. April.

Robert Thompson / Lichen (Xanthoria aureola) Melmore Head, County Donegal, Republic of Ireland. February

Paul Harcourt Davies / Xantheria lichen (Xanthoria aureola) wall lichen growing near Orvieto, Italy

Nick Upton / Common orange lichen (Xanthoria parietina) with many cup-shaped apothecia fruiting bodies, growing on Hawthorn branch (Crataegus monogyna) in early spring, Wiltshire, UK, March.

Staffan Widstrand / Lichen (Xanthoria sp), Svalbard, Norway

Staffan Widstrand / Lichen (Xanthoria sp) growing on rocks by coastline, Svalbard, Norway

Adrian Davies / Beach woodlouse (Ligia oceanica) on lichen (Xanthoria parietina), Devon, England, UK, July.

Alex Hyde / Lichen (Xanthoria parietina) photographed on a white background. This species is very resistant to air pollution. Peak District National Park, UK, January.

Alex Hyde / Lichen (Xanthoria parietina) found growing on a twig, showing mass of apothecia (cup-shaped fruiting bodies). This species is very resistant to air pollution. Peak District National Park, UK, January.

Alex Hyde / Lichen (Xanthoria parietina) found growing on a twig, showing mass of apothecia (cup-shaped fruiting bodies). Peak District National Park, UK. January.

Adrian Davies / Lichen (Xanthoria parietina) on tombstone in churchyard, Devon, UK, August

Adrian Davies / Orange coloured Seashore Lichens (Xanthoria parietina) and Sea Ivory (Ramalina siliquosa) UK, August

Adrian Davies / Orange coloured Seashore Lichens (Xanthoria parietina) and Ochrolechia parella. UK, August

Adrian Davies / Close up of Lichen (Xanthoria parietina) Devon coastline, England, UK

Edwin Giesbers / Maritime sunburst lichen (Xanthoria parietina) on rock, Menorca, Balearic Islands, Spain, Europe

Robert Thompson / Lichens {Xanthoria parientina} and {Tephromela atra} Grange, County Silgo, Northern Ireland, UK. August

Robert Thompson / Lichen {Xanthoria aureola} Killard Point NNR, County Down, Northern Ireland, UK, October

Robert Thompson / Lichens {Xanthoria parientina}, {Caloplaca thallincola} and {C. verruculifera} Killard Point NNR, County Down, Northern Ireland, UK, September

Robert Thompson / Lichen {Xanthoria ectaneoides} Killard Point NNR, near Strangford, County Down, Northern Ireland, UK

Robert Thompson / Lichen {Xanthoria parietina} on rocks, Grange, County Sligo, Republic of Ireland, August

Ross Hoddinott / Yellow Scales lichen {Xanthoria parietina} growing on brick wall, Mevagissey, Cornwall, UK. May 2009.

Ross Hoddinott / Yellow scales lichen (Xanthoria parietina), growing on wooden post, nr Bradworthy, Devon, UK. October

Adrian Davies / Lichen {Xanthoria parietina} on flint wall, UK, a useful monitor of pollution levels.

Ross Hoddinott / Yellow scales lichen {Xanthoria parietina} growing on groyne, Exmoor National Park, Somerset, UK. October

Ross Hoddinott / Yellow Scales lichen {Xanthoria parietina} growing on stone, Exmoor National Park, Somerset, UK. October

Ross Hoddinott / Mixed lichens, including Yellow scales lichen {Xanthoria parietina} growing on stone wall, Cornwall, UK. November

Ross Hoddinott / Lichen {Xanthoria parietina} growing on stone, Exmoor National Park, Somerset, UK. October

Martin Gabriel / Lichen on stone, Namibia

Niall Benvie / Lichen on stone, Scotland, UK

Adrian Davies / Seashore lichens Xanthoria parietina (orange) and Ochrolechia parella (grey), UK

Adrian Davies / Lichen {Xanthoria parietina} growing on stone, UK

Chris O'Reilly / Lichen {Xanthoria parietina} growing on stone wall, Yorkshire, UK

Martha Holmes / Lichen {Xanthoria parietina} growing on stone wall, Yorkshire, UK

Adrian Davies / Lichen {Xanthoria parietina} growing on gravestone, UK

Adrian Davies / Lichen {Xanthoria parietina} growing on stone, UK

Ross Hoddinott / Lichen (Xanthoria parientina) growing on paint of tractor trailer. Devon, UK.

Ross Hoddinott / Lichen (Xanthoria parientina) growing on paint of tractor trailer. Devon, UK.

Geoff Simpson / Xanthoria lichen, Gwynedd, Wales

Chris O'Reilly / Lichen on stone wall {Xanthoria parietina} Yorkshire Dales NP, UK

Richard Du Toit / Lichen {Xanthoria sp} Skeleton Coast NP, Namibia

Chris O'Reilly / Lichen on stone wall {Xanthoria parietina} Yorkshire Dales NP, UK

Nick Upton / Limestone rocks high just above the high tide line with patches of Common orange lichen (Xanthoria parietina) and Black Tar lichen (Hydropunctaria maura / Verrucaria maura). Rhossili, The Gower Penins...

Nick Upton / Limestone rocks high just above the high tide line with two Small periwinkles (Melarhaphe neritoides = Littorina neritoides) among patches of Common orange lichen (Xanthoria parietina) and Black Tar l...

Nick Upton / Limestone rocks high just above the high tide line with two Small periwinkles (Melarhaphe neritoides = Littorina neritoides) among patches of Common orange lichen (Xanthoria parietina) and Black Tar l...

Adrian Davies / Lichen on stone {Xanthoria parietina} Devon UK

Will Watson / Jelly ear fungus (Auricularia auricula judae) growing on Elder (Sambucus nigra) tree branch with Maritime sunburst lichen (Xanthoria parietina), Stocking Meadow Nature Reserve, Herefordshire, England,...

Robert Thompson / Lichens (Parmelia sulcata) and (Xanthoria parietina) growing on apple twigs, Peatlands and Annagarriff wood National Nature Reserve, Portadown, County Armagh, Northern Ireland, UK. September.

Nick Upton / Sunburst lichen (Xanthoria parietina) growing on limestone cliff tops at Stackpole Head, Pembrokeshire, Wales, UK, August.

Adrian Davies / Lichen (Xanthoria parietina) growing on gravestone in churchyard, Tintagel, Cornwall. May.

Adrian Davies / Lichen (Xanthoria parietina) growing on brick wall, does not grow on mortar, Romney Marsh, Kent, UK. June.

Robert Thompson / Branch covered with different lichens including Xanthoria parietina, Lecanora chlarotera with a lichenicolous fungus, Evernia prunastri and Physcia sp, Banbridge, County Down, Northern Ireland.

Robert Thompson / Branch covered with different lichens Xanthoria parietina, Physcia tenella, Physcia adscendens, Peatlands & Annagarriff Wood NNR, County Armagh, Northern Ireland.

Adrian Davies / Seashore lichen (Xanthoria parietina) on rock. Cornwall, England, UK. July.

Nick Upton / Rock samphire / Sea Fennel (Crithmum maritimum) clumps flowering among coastal rocks encrusted with Common orange lichen (Xanthoria parietina), Rhossili, The Gower, Wales, UK, August.