The unnatural history of the lichen Rhizocarpon geographicum

Richard A. Armstrong

Research output: Contribution to specialist publication or newspaperArticle


One of the most widely distributed species of crustose lichen is Rhizocarpon geographicum. This unusual organism comprises yellow-green 'areolae' growing on the surface of a non-lichenised hypothallus that extends beyond the margin of the areolae to form a ring. This article describes the general structure of R. geographicum, how the areolae and hypothallus are formed, why the species grows so slowly, and whether it can inhibit its neighbours by releasing allelochemicals.
Original languageEnglish
Number of pages4
Specialist publicationMicrobiologist
Publication statusPublished - Jun 2007


  • crustose lichen
  • Rhizocarpon geographicum
  • allelochemicals


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