Mycologia Europaea 1: 242. 1822.
Common Name: none
Fruiting body sessile, 0.5-3.5 cm broad, at first subglobose to slightly urn-shaped, becoming shallowly cupulate to nearly flat in age; margin incurved when young , then upturned, plane, to recurved, sometimes wavy; exterior surface pale-lilac in youth, then whitish to pale-tan, glabrous or furfuraceous; interior surface (hymenium) glabrous, violet in youth, dull-brown to blackish-brown at maturity; context 0.5-2.0 mm thick, pallid, somewhat translucent; odor and taste not distinctive.
Spores 13.5-15.5 x 7.5-8.5 µm, ellipsoid, smooth, thin-walled, typically eguttulate, some with an indistinct central body; immature spores often containing one to several granules; asci tips blue with Meltzer's reagent; spore deposit not seen.
Scattered to clustered on burnt soil, charred wood, etc., during the spring; widely distributed but most common in montane regions following forest fires.
Edibility unknown; insignificant.
The purple color of this attractive cup fungus is best seen in young fruiting bodies growing in shaded locations, e.g. the underside of a burned log or rock. When exposed to sunlight, specimens soon fade to a nondescript brown and are less recognizable. Peziza violacea is part of a group of Ascomycetes that fruit after forest fires. Sometimes called "fire-cups," they often carpet the ground, and are occasionally used as an indicators for morels which may subsequently fruit in the same area. A partial list of "fire cups" includes: Pyronema domesticum, Anthrocobia macrocystis, Geopyxis carbonaria, Plicaria endocarpoides, Tricharina gilva, and the very similar Peziza pratervisa. Except for the latter, most of these can be distinguished by color, shape, or the presence or absence of hairs. To separate Peziza violacea from P. praetervisa, also common in California, requires a microscope. The spores of the latter are warted and contain two oil drops at maturity.
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