Images of British Lichens
Arthonia spadicea Leight.
Thallus thin, greenish grey, or more often immersed in the substrate surface, with embedded, red-brown to black, rounded, flat to somewhat convex, rather shiny apothecia; ascospores 1-septate. On very shaded bark, generally near the bases of trunks, usually of deciduous trees (but photographs below from pine in a somewhat nutrient-rich situation), widespread and often common. Generally recognisable in the field by its "tar spot" appearance, but part of a large genus in which chemical tests and microscopic examination are important.
Refs: Smith et al. (2009), 169; Purvis et al. (1992), 86; Dobson (2005), 69 (photo); Dobson (2011), 76 (photo); van Herk & Aptroot (2004, 2013), 62-3 (photo); Arup et al. (1997), 164 (photo); Puntillo (1996), plate 4 (photo); Wirth, Hauck & Schulz (2013), 1: 166 (photo), 167.
|On Scots Pine (Pinus sylvestris) trunk, Ballygrant, Islay, May 2011, BLS meeting (material lent by Peter Scholz)|
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Uploaded February 2013, last updated January 2016