Hi Alan
This is clearly Hymenoscyphus menthae (= H. consobrinus). You may consult my paper on this:

Hymenoscyphus menthae, H. macroguttatus and H. scutula, a
comparative taxonomic study emphasizing the value of spore
guttulation and croziers. Ascomycete.org, 7 (6) : 255-287. (2015)

Typical are the navicular multiguttulate, homopolar spores without a perceptible upper end.

This is a plurivorous species, like H. epiphyllus which differs in a consistently short stout stipe, and spores with large and small drops, also in having croziers at the ascus base.

Urtica and Rubus are very easily separated in a cross section. Urtica 4-angled with cavities in the xylem.

Zotto

das ist sehr hilfreich, Zotto, danke