pf339's picture

White thallus with yellow apothecia

Observed: 15th January 2013 By: pf339
S159 Neighbourhood Nature - course complete
pf339’s reputation in Fungi and Lichenspf339’s reputation in Fungi and Lichenspf339’s reputation in Fungi and Lichenspf339’s reputation in Fungi and Lichens
White thallus with yellow apothecia 1
White thallus with yellow apothecia 2
White thallus with yellow apothecia 3
White thallus with yellow apothecia 4
White thallus with yellow apothecia 5

White, crustose thallus with yellow lecideine apothecia (K+ crimson) growing on south facing, sloping limestone ledge in church wall. Thallus seems to follow possible water drainage pattern (picture 5). Pictures 1 and 2 show same apothecia wet then dry from thallus shown in picture 5. Pictures 3 and 4, from 50cm along ledge, show same apothecia wet then dry. (‘Wet’ from 15 Jan after overnight thaw of 3cm snow, ‘dry’ after windy, sunny day at end of Jan.) Possibly Caloplaca lactea.


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

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

  • Caloplaca lactea
    Confidence: It might be this.
    Likely ID
    Caloplaca marmorata
    Confidence: I'm as sure as I can be.
Species interactions

No interactions present.


synan's picture

Tentative agreement...

based on the concave apothecia, translucent when wet, not on any personal experience of this species!


Edit: Just read the Bulletin (thanks go to Alan), reinforcing the impression I already had - that Caloplaca is a major headache. A photo of some of the material referred to in the analysis:

2nd Edit: The link I had given no longer points to C. marmorata, so the site must have been changed. The photo of the British material is the 'Powell 1944' sample at:

(1944 being the herbarium accession number, not the year it was collected).

pf339's picture


Thanks for all help with identification.
Nigel, many thanks for http site.
Alan, thanks for introducing me to C. marmorata. Interesting to learn of a wildlife species that may have a particular association with Cambs and nearby and is not found in a fen. (I do like those that live in a fen as well, of course.)

AlanS's picture

Clarifying my comment

I assume that most British "C. lactea" is C. marmorata, which gives it a much greater range than North Essex and Cambridgeshire. I was pointing out that it nevertheless seems to be a thing to find on 'consecrated' limestone, both in North Essex where I occasionally potter, and Cambs where you operate, Phil.

By the way, Nigel, thanks for the revised link. I had looked at Kondrak's site but missed this gallery - and reassuring to note that C. crenulatella there is a very good match to what I have been calling C. crenulatella in my favourite Essex churchyard!


pf339's picture

2nd Edit

Thanks for second link. Just scrolled through and can understand your 'major headache' reference.