The fungus, originally collected from Muskingum County, Ohio, was named Peziza occidentalis by Lewis David de Schweinitz in 1832.

[8][9] The cladistic analysis combined comparison of sequences from the internal transcribed spacer in the non-functional RNA with fifteen traditional morphological characters, such as spore features, fruit body shape, and degree of hair curliness.

Based on this analysis, S. occidentalis is part of a clade of evolutionarily related taxa that includes the species S. dudleyi, S. emarginata, S. hosoyae, S. korfiana and S. mesocyatha.

[11] Anamorphic or imperfect fungi are those that seem to lack a sexual stage in their life cycle, and typically reproduce by the process of mitosis in structures called conidia.

[14] Depending on their age, the fruit bodies of S. occidentalis may range in shape from deep cups to saucers to discs in maturity, and they can reach diameters up to 2 centimetres (3⁄4 inch).

The asci (filamentous structures in which the ascospores develop) are cylindrical with gradually tapering bases, eight-spored, and measure 240–280 by 12–15 μm.

The paraphyses (sterile, filamentous hyphae present in the hymenium) are cylindrical, 2–3 μm thick, barely enlarged at their apices, straight, and mostly unbranched above.

The two also differ in seasonal and geographic distribution: S. occidentalis fruits from late spring to early autumn in the United States, while S. coccinea fruits earlier in spring,[15] and is distributed in eastern North America, in the midwest, in the valleys between the Pacific coast and the Sierras and Cascades, as well as Europe, Africa, Australia, and India.

[13] Melastiza species usually lack stems and Phillipsia domingensis produces purplish or dark red cups with white undersides.

[23] As a saprobic fungus, S. occidentalis is part of a community of fungi that play an important role in the forest ecosystem by breaking down the complex insoluble molecules cellulose and lignin of wood and leaf litter into smaller oligosaccharides that may be used by a variety of microbes.

[24] Fruit bodies of S. coccinea may grow either solitarily, scattered or grouped together on sticks, twigs, and fragments of dead wood,[17] usually somewhat decomposed and partially buried in the top 5 cm (2 in) of soil and forest litter.