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Species Information
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.
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.
Upper surface: 0.05cm, developing out of dark spots under the surface of the leaf, breaking them open, and then delicately bordered by remains of epidermis; disc-shaped to cup-shaped; spore-bearing upper surface olive-brownish, (Breitenbach), about 0.05cm across, erumpent from small dead spots of leaf tissue, saucer-shaped, closely appressed to leaf; disc flat, yellowish-gray, smooth, (Dennis), 0.03-0.05cm wide, submerged, becoming erumpent, at first closed, opening and becoming nearly flat; brownish, waxy, (Seaver)
Underside: brown (Dennis)
Stem: "embedded in the epidermis of the upper side of the leaf", "clinging closely to the tissue of the leaf", (Breitenbach), on brown spots 0.1-0.3cm across (Seaver)
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)
Habitat / Range
gregarious to cespitose, on upper sides of green leaves of Trifolium spp. (clover), in fall, (Breitenbach), on living leaves of Trifolium spp., May to November, (Dennis), gregarious to cespitose, on living leaves of species of Trifolium (clover), (Seaver)
