Growing on a roadside wall.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
You had me confused for a moment! Doing a bit of continent hopping for Christmas?
Candelariella vitellina usually comes with a granular crust and there doesn't appear to be much of a thallus here. It might be a Caloplaca (K+ crimson vs no reaction with Candelariella) - possibly the C. holocarpa group. Let's hope someone more knowledgeable about these two genera stops by.
Already got quite a few pics to put up - was hoping to be able to name some first - but not as easy as one thinks.
Also wondering how popular I'd be if I started putting chemicals on walls and trees in London.
Lat/Lng: 51.5034, -0.026
OS grid ref: TQ371801
On the wall alongside the building site.