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Lichen: Xanthoria polycarpa

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Name: Xanthoria polycarpa (Hoffm.) Th.Fr. ex Rieber

web800-Xanthoria-polycarpa: note the coral-like appearance of the lobes. Photographed in Stephen's Green, Dublin.

Xanthoria polycarpa: note the coral-like appearance of the lobes. Photographed in Stephen's Green, Dublin.

Pronunciation: Xanthoria polycarpa

Conservation Evaluation: Least Concern Body Type: Foliose

Description: Thallus is yellow in colour, small in size and rosette shaped usually with abundant apothecia. It rarely grows larger than 3cm and is typically in the range of 0.5cm to 2.5cm in diameter. The lobes are convex and sometimes pale greenish at the margins. An old descriptive term is the sunburst or pin-cushin lichen. The lobes are branched, narrow and often crenulate; they widen towards the apex reaching a width of 1 mm. The under surface is white with short attachment structures or hapters. Overall it looks coral-like and is brittle to the touch.

Xanthoria polycarpa on a twig. Note the small size and the abundance of apothecia and its position in the axil.

Xanthoria polycarpa on a twig. Note the small size and the abundance of apothecia and its position in the axil.

The apothecia are characteristically abundant and range widely in size from 0.5mm to 4.5mm in diameter. They are frequently contorted and peltate (shield shaped). The disc typically stays very orange. Soredia and isidia are absent.

Spores are ellipsoidal with a size range of 11-15 by 5-8µm.

Chemical Tests: K+ purpleVice county distribution map

Nature Notes: Locally common on fences and in parks and gardens. Found on dead and living twigs and in the axil of wide spreading branches, particularly fond of Poplar, Larch and Salix species. Shaded specimens take on a light yellow to grey hue. The small yellow tightly knit clusters of apothecia help in its identification.

The apothecia may be infected with Lichenoconium xanthoriae.

Vice County Distribution: See Map

Link: Map this species on the Lichen Survey

Other Xanthoria recorded in Ireland

  • Xanthoria calcicola Oxner
  • Xanthoria candelaria (L.) Th.Fr.
  • Xanthoria ectaneoides (Nyl.) Zahlbr.
  • Xanthoria elegans (Link) Th.Fr.
  • Xanthoria parietina (L.) Th.Fr.
  • Xanthoria ulophyllodes Räsänen [42]

Text and images © Paul Whelan, 2009.