lpearce's picture

Crescent map lichen

Observed: 8th November 2009 By: lpearcelpearce’s reputation in Fungi and Lichenslpearce’s reputation in Fungi and Lichenslpearce’s reputation in Fungi and Lichens

Found this on a wall of a old clearance house.Thought it might be Rhizocarpon geographicum but the colour and appearance does seem to match the image on http://www.britishlichens.co.uk/species/Rhizocarpon%20lecanorinum%20smal...


Caution: Do NOT use iSpot to identify fungi to eat!

Some fungi are very poisonous so a mistaken ID could have serious consequences.

Species interactions

No interactions present.


Stumpy's picture

Yes looks the same to me

Yes looks the same to me aswell.

I'm a student so be gentle.

gardener's picture

Not sure - Rhizocarpon

Not sure - Rhizocarpon species can be very difficult!
R. geographicum is more likely, it's widespread and very variable.
The only way to tell for sure is to cut one of the apothecia (black fruit) in half and look at the colour under your microscope:
R. geographicum - chestnut (K+ crimson) or more rarely dark green with a weaker K reaction.
R. lecanorinum - pale green-brown, K-

AlanS's picture

These can be difficult

As Jenny says, this pair of species are not always easily identified in the field (though are more easily distinguished when they are growing together).

The cited photograph of R. lecanorinum from britishlichens.co.uk is correctly named, but does not show the areolar shape (the yellow 'islands') as well as usual - nevertheless the photograph posted here does not match it. Sorry.

R. geographicum is very variable and several subspecies have been recognised in the past.