... The shiny, slightly raised groups of perithecia are visible on both leaf surfaces but mainly on the upper surface ... Although the ascocarps are conspicuous on leaves in the growing season, they do not mature until the following spring. This species occurs across Canada on [Betula nana, B. papyrifera] and other species of Betula ...
”- Parmelee, J.A.: (1988) Parasitic fungi of Newfoundland based on specimens from Gros Morne National Park©
Reference: https://www.biodiversitylibrary.org/page/28243715#page/467/mode/1up