What You Should Know
Hymenoscyphus fructigenus is a tiny cup fungus with caps maxing out at 4 mm. Growing in clusters on beechnuts, hickory shells, and acorns. It is often found fruiting alongside Mycena luteopallens a tiny gilled mushroom that seems enormous by comparison, since a single hickory shell can hold dozens of specimens of Hymenoscyphus fructigenus.
Other names: Acorn Cup Fungus.
Hymenoscyphus fructigenus Mushroom Identification
1 - 2 (5) mm, disc-shaped, slightly depressed, on the stalk, with age with raised, wavy edge, white, whitish, creamy, pale yellowish. The hymenial layer is smooth, white, cream, or pale yellow, located on the inner surface.
0.5 - 5 mm high, 0.1 - 0.3 mm in diameter, cylindrical, narrowed down, uneven, finely pubescent, whitish or yellowish, at the base with a reddish tinge.
100-120 * 9-10 microns, club-shaped. Spores 20 * 5 microns.
The flesh is thin, light, and odorless.
Hymenoscyphus fructigenus Synonyms
Leptostroma virgultorum var. fructigenum (Bull.) Rehm
Peziza fructigena Bull., 1785
Peziza virgultorum var. fructicola Wallr., 1833
Helotium fructigenum (Bull.) P. Karst., 1871
Phialea fructigena (Bull.) Gillet, 1881
Helotium virgultorum var. fructigenum (Bull.) Rehm, 1893
Ciboria fructigena (Bull.) Killerm., 1935
Photo 1 - Author: Fluff Berger (Creative Commons Attribution-Share Alike 4.0 International)
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Photo 3 - Author: Eugene Popov (Creative Commons Attribution 4.0 International)
Photo 4 - Author: Fluff Berger (Creative Commons Attribution-Share Alike 4.0 International)