Summary:
Auricularia americana group fungi grow on wood, producing an ear-shaped to inverted cup-shaped fruitbody which is red-brown, cinnamon, yellow-brown, olive-brown, or blackish brown. Flesh is thin rubbery to flabby-gelatinous. The convex upper sterile surface has a dense, silky covering or is minutely hairy. The concave lower fertile surface is smooth. Both surfaces are often irregularly ribbed and veined. The species in the group as considered here correspond to the phylogenetic Auricularia auricula-judae complex. Members of this group include at least two North American members, Auricularia americana (which also grows in Asia) and Auricularia angiospermarum. These two are separated by molecular study and habitat: the former grows on conifer wood and the latter on hardwood. The group also includes the inaptly named European species Auricularia auricula-judae (common in central Europe). A. auricula-judae has larger fruitbodies than A. americana, larger spores, and typically grows on hardwood. According to Wu(1), a fourth species, Auricula heimuer, is likely to have been the taxon reported 2000 years ago in the Chinese medical book "Shennong''s Compendium of Materia Medica". It has been cultivated in China for more than 1400 years for its food and medicinal properties. A. heimuer is the center of an industry reported to be producing 4.75 billion kg (fresh weight) in 2013 valued at 4 billion US$ (Wu(1)). The other four known species in the group are Auricularia villosula (China where it is also cultivated by farmers, Russia), Auricularia minutissima (China, Russia), Auricularia tibetica (conifers, Tibet in China), and Auricula minor (Papua-New Guinea). One or more members of this group are said to be edible (Phillips, Lincoff(2)), but one or more members of this group are reported to affect blood coagulation, (Lincoff(2)). The edibility value is more in texture than flavor (Lincoff(1)).

Microscopic:
spores 12-14 x 4-6 microns, allantoid, colorless, white in mass; hymenium a dense layer of cylindric-fusiform basidia, (Martin), spores (12.5)13-15 x (4.5)4.8-5.5(6) microns, allantoid, smooth, colorless, thin-walled, (Wu(1) for A. angiospermarum), spores 17-19 x 6-8 microns, cylindric, slightly curved, smooth, inamyloid, colorless, some with droplets; basidia up to 80 x 7.5 microns, cylindric, with 3 transverse septa, with 3 lateral epibasidia and 1 terminal; cystidia none; hairs on upper side colorless, cylindric, pointed, 80-200 x 5.5-7.5 microns; hyphae gelatinized, branched and some with gnarled outgrowths, 1.5-4 microns across, septa without clamp connections, (Breitenbach)

Notes:
The distribution of Auricularia americana group includes BC, WA, OR, ID, AB, MB, NB, NF, NS, ON, PQ, YT, AL, AK, AR, AZ, CA, CO, CT, FL, GA, IA, IN, KS, KY, LA, MA, MD, ME, MN, MO, MS, MT, NC, NE, NH, NJ, NY, OH, PA, SC, TN, TX, UT, VA, and WV, (Ginns), North America, Europe, and Asia, (Breitenbach), Armenia, Azerbaijan, Estonia, Georgia, Latvia, Lithuania, and Russia, (Raitviir), and Mexico (Lowy). Auricularia americana was examined from MI, WI, China, and Russia; Auricularia angiospermarum was examined from AZ, CT (type), IL, and WI; Auricularia auricula-judae was examined from Czech Republic, Denmark, France, Germany, and Russia (West Caucasus); Auricularia heimuer, A. minutissima, and A. villosula were each examined from China and Russia, Auricula tibetica was examined from Tibet in China, and Auricula minor was examined from Papua New Guinea, (Wu(1)).