• Rhizocarpon subgeminatum Eitner
Rhizocarpon subgeminatum
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(Map updated: 11 August 2009)

The thallus of this dark grey to dark brown crustose lichen is rather small and areolate (cracked like a mirror), and scattered over the tops and sides of nutrient-enriched siliceous rocks and boulders. The colourless, muriform spores (usually two spores per ascus) and K- epithecium separate it from R. geminatum which has brown spores and grows in an altogether different habitat. In Ireland, it is known on rocks in Connemara but is likely to occur more widely.

Key characteristics

  • Thallus, areolate, mostly brown-coloured; tops and sides of granitic rock
  • Epithecium K- (with green glow), asci one- to two-spored (occasionally four-spored); spores persistently colourless.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Rhizocarpon subgeminatum Eitner. [In] LichenIreland. Accessed on 2019-05-21.