Images of British Lichens
Physcia tribacioides Nyl.
Foliose, ash-grey but not pruinose, more greenish when damp, lobes without pseudocyphellae, adpressed, widened towards the crenately notched tips, soralia white, mostly laminar and hemispherical; apothecia very rare. On bark of naturally nutrient-rich trees, especially in churchyards and old parkland, mainly near the south coast but now nationally rare, extinct in much of its former range and confined to south-western England and south-west Wales (also S.W. Ireland), much reduced by loss of old elms and now threatened by atmospheric deposition of agricultural nutrients. [In the field, this species can look a lot like Diploicia canescens, which also grows on Quercus ilex at Orielton.]
British Red Data Book species: endangered; scheduled protected species, Wildlife and Countryside Act 1981.
Refs: Smith et al. (2009), 703; Purvis et al. (1992), 469; Dobson (2011), 342-3 (photo) [Dobson (2005) is mixed concept]; Church et al. (1996), 58; Whelan (2011), 131 (photo); Lichen Atlas of the British Isles 3: 1123 (1998).
|On Holm Oak (Quercus ilex), Orielton, Pembrokeshire, May 2009|
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Uploaded July 2009, last updated May 2012