Orange rust found on the underside of a white poplar leaf, caused, I understand, by Melampsora sp.
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.
Normally these rusts are found on Rosa and many other trees and shrubs. I cannot id by photographs but would be happy to receive a leaf in the post for microscopic examination.
Wild Flower Society member
See also Exobasidium's comment at http://www.ispot.org.uk/node/17446
You can download a copy of "The British Rust Fungi" from:
See page 337
Thank you for your comments and references.
If I can find the leaf the next time I am in the area I will forward it.
Lat/Lng: 52.7, -2.6
OS grid ref: SJ6412