Fruiting body a stipitate cup, 0.5-2.0 cm broad, shallowly to deeply concave; margin incurved to upturned; hymenium dark-brown to black, glabrous; exterior of cup blackish, smooth, becoming wrinkled with age or drying, covered with matted, dark-grey hairs; odor and taste not determined.
Stipe 2.0-5.0 cm long, 1.0-3.0 mm thick, slender, narrowed below; surface blackish-brown, appressed fibrillose; loose cottony black mycelium at base.
Spores 21.0-28.0 x 9.0-13.0 µm, elliptical, finely warted, whitish in deposit.
Solitary to scattered on decaying conifer litter or wood; fruiting in the spring near melting snow; common in the Sierra and higher elevations of the Coast Range.
Plectania nannfeldtii is a common, montane Ascomycete, though typically overlooked unless silhouetted against snow. The black stipitate cups are distinctive and unlikely to be confused with other cup fungi. The spring Ascomycetes that do form stipitate cups, are either smaller or differently colored.