• Haematomma ochroleucum var. porphyrium (Pers.) Laundon
Haematomma ochroleucum var. porphyrium
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(Map updated: 11 August 2009)

This grey-white, powder-cottony, crustose lichen should be looked for on dry, siliceous or slightly calcareous rocks and walls where it can spread to form big-sized patches. The edge of the thallus is ringed by a conspicuous white-fringed border. Discs are small and red and are scattered like little spots of blood. A dab of K (Potassium hydroxide) will turn the thallus yellow. Pd turns it yellow.

Key characteristics

  • White, circular patches with a powdery or cottony thallus surrounded by a chalk-white fringe like rug edging
  • On vertical sandstone walls and gravestones.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Haematomma ochroleucum var. porphyrium (Pers.) Laundon. [In] LichenIreland. Accessed on 2019-01-19.