E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Ciboria caucus forms brown cups with stems, growing on fallen catkins of Populus. Hansen, L.(1) give C. amentacea (Balb.) Fuckel as a synonym of this species.

It is from found NY to OR and MB, as well as in Europe, (Seaver), and according to Kanouse from WA. There is collection from BC at the Pacific Forestry Centre.

Upper surface:
0.2-0.8cm wide, cup-shaped with incurved margin, expanding to saucer-shaped or somewhat disc-like; brown, (Seaver), 0.4-1.5cm wide, pale to medium brown, (Hansen)

Stem:
0.2-0.8cm long and 0.5cm wide, (Seaver), 0.5-3.5cm x 0.03-0.17cm (Hansen)

Microscopic:
spores 9-10 x 5-6 microns, elliptic or somewhat elliptic, colorless; asci 8-spored, reaching 130 x 9 microns, cylindric-clavate, (Seaver), spores 7.5-10(11.5) x 4.5-6 microns (Hansen)