Host is Mercurialis perennis
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
What is the host, Martin - Mercurialis? Your species uses Larix and Populus, which this is obviously not. Could it be Melampsora populnea which does use Mercurialis as a host?
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
I thought it was Melampsora populina but this name is apparently invalid? Then I got confused. Thanks for the clarification.
Lat/Lng: 52.1376, -0.1274
OS grid ref: TL282504