Wynnea americana, commonly known as moose antlers or rabbit ears, is a species of fungus in the family Sarcoscyphaceae.

It is distinguished from other species in its genus by the pustules (small bumps) on the outer surface, and microscopically by the large asymmetrical longitudinally ribbed spores with a sharply pointed tip.

[2] In 1946, French mycologist Marcelle Louise Fernande Le Gal determined that the ascus in W. americana was similar in structure to those species he placed in the suboperculate series.

[5] The fruit bodies (technically called apothecia) of W. americana are erect and spoon- or ear-shaped, and may reach up to 13 centimetres (5 inches) tall by 6 cm (2+1⁄4 in) wide with the edges usually rolled inward.

[7] The sclerotium's function is thought to supply moisture and nutrients,[1] or to serve as a resistant structure capable of sustaining the fungus through times of stress.

The presence of the apical ring beneath the operculum and the slanted opening that results is a condition known as "suboperculate",[12] and is shared with Cookeina tricholoma and Phillipsia domingensis, also in the family Sarcoscyphaceae.

[2] The structure of the septa has been investigated using transmission electron microscopy, which has revealed that W. americana has a single pore plugged by a "fan-shaped matrix"—an electron-dense region with a torus-shaped ring of translucent tissue wrapped around it.

[4] In comparison to W. americana, W. gigantea has apothecia that are smaller, more rounded at the tips, more numerous in a single specimen, and paler in color.

[2] It also may resemble the purplish-brown and relatively stout Otidea smithii, as well as Mitodis lingua, the inside of which is darker than the outside; neither of these are connected to dense below-ground tissue.

[19] The fruit bodies grow solitarily or in clusters on the ground in deciduous forests, and prefer moist, organic soils.