Summary:
Features include minute, saucer-shaped to disc-shaped fruitbodies breaking out of brown spots on clover leaves, with olive-brown to yellowish-gray upper surface and brown exterior, clinging closely to the leaf, and microscopic characters.

Microscopic:
spores 10-14(16) x 4.5-5 microns, irregularly oval, smooth, colorless, with 2 droplets, biseriate; asci 8-spored, 70 x 13 microns, negative reaction to iodine; paraphyses cylindric, septate, sometimes forked, with slight clavate widenings to 4 microns toward tips, (Breitenbach), spores 10-12 x 5-5.5 microns, slightly ovoid, non-septate, with a small oil-drop near each end, irregularly biseriate; asci 8-spored, up to 80 x 14 microns, cylindric-clavate, pore not turning blue with iodine; paraphyses about 3-4 microns wide at tip; no true cellular excipulum flanking the hymenium, (Dennis), spores 10-15 x 5-7 microns, elliptic or oval, simple, usually with one oil drop; asci 8-spored, reaching a length of 60-80 microns and a width of 10-14 microns, clavate; paraphyses filiform [thread-like], widened in upper part, 3-4 microns wide, (Seaver)

Notes:
Pseudopeziza trifolii is found probably throughout North America where clover grows, and also Europe including Switzerland and the United Kingdom. There are collections from BC deposited at the Pacific Forestry Centre and the University of British Columbia.

Synonyms and Alternate Names:
Discina apiculata McKnight
Discina olympiana Kanouse