Tom Volk's Fungus of the Month for April 2004

Auricularia auricula-judae, wood ear or cloud ear mushroom a.k.a. Judas' ear fungus, in honor of Easter

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Auricularia auricula-judae

This month's fungus, Auricularia auricula-judae, is one of the jelly fungi. All of the jelly fungi are Basidiomycota with unusual jelly-like texture. Most are more solid than jelly that you spread on bread, with a texture similar to that of Gummi BearsTM. The "jellys" are fun fungi to find in the woods and can be found very soon after a rainfall. Most of them have the uncanny ability to dry out then rehydrate, and you will likely be able to find them even in the early spring as leftovers from last year, even if you're in the far north. When you're out in the woods with your friends, it's nice to have a stories to tell, and we hope you will learn much about this fungus on this page.

The common name Judas's ear comes from the legend that Auricularia formed its ear-shaped fruiting bodies as a curse on the tree on which Judas hanged himself. If you don't remember your New Testament (or care about it), Judas was the apostle who betrayed Jesus for 30 pieces of silver. Obviously someone had an overactive imagination when seeing an ear on a tree and thinking of Judas. However the intriguing name has stuck, even with the normally stuffy taxonomists. In fact "Auricularia" means ear and the epithet "auricula-judae" means "the ear of Judas." Since the mushroom is particularly prevalent on menus in Oriental restaurants, more preferred names would be the "wood ear mushroom" or the "cloud ear mushroom," Some would consider other translations of the name perjorative, and hence I have not mentioned them here. Sometime the scientific name is listed as Hirneola auricula. It seems likely that Auricularia polytricha, cultivated for use in Oriental dishes, is a very close relative or even the same species. However, it certainly can be much larger and tends to grow in subtropical to tropical areas. It is easily available in dried form in almost every oriental food store, in specialty food markets, and even in many large grocery stores.

Jelly fungi

another view of Auricularia auricula-judaeIt would be good at this point to discuss the many different kinds of jelly fungi. There are three unrelated orders of fungi that fall under the common name of jelly fungi: Auriculariales (the ear jelly fungi), Tremellales (the jelly fungi), and Dacrymycetales (the tuning fork jelly fungi). Members of the Tremellales tend to be of a softer texture and more easily "squished" than the other two phyla, although there are exceptions. They range in color from brown to yellow and even white. I've already had Tremella mesenterica as Fungus of the Month-- you may remember it as Witch's butter. The Dacrymycetales typically are tougher and more orange in color, although there is at least one brown species, Dacryopinax elegans, that can cause major confusion for identifiers. The Auriculariales are characterized by their typically brown colors and are known for their tough, rubbery consistency. However when dried they become very horny (get your mind out of the gutter-- I mean hard like a cow's horn...) and do not closely resemble the fresh fruiting body. It takes some practice to be able to identify the orders using only macroscopic characteristics. It can sometimes help to use ecology as a character-- typically the Auriculariales and Dacrymycetales are good wood-decay fungi, while many of the Tremellales are parasites on other living fungi.

However, if you have a microscope, classification of the jelly fungi into these orders is relatively easy, as long as the fruiting bodies are in the proper stages of development. The orders can be distinguished from one another by observation of their basidia. The Auriculariales have transversely septate basidia, perpendicular to their direction of growth. The Tremellales have cruciate-septate basidia (vertically septate, parallel to their direction of growth). The Dacrymycetales have aseptate basidia in the shape of tuning forks. However, the basidia are not always easy to see. The major trick for microscopic identification of the orders is to chop and squash the fresh or revived fruiting bodies enough to be able to tease out the basidia from the surrounding gelatinous matrix. You must also realize that the basidia are largely buried below the surface of the fruiting body, with only the basidiospores visible on the surface; that's why the chopping is necessary.

types of basidia- see text for details Types of basidia

In the above collage, note that #1 is stained with Melzer's reagent, while #2, #3, and #4 are stained with 3% phloxine. Also note that even if you only find dried fruiting bodies, you can make a moist chamber in a sealed container with a small piece of wet paper towel to revive the fruiting bodies, which will begin to form spores again. See below for drawings of four kinds of basidia by my student Maria Lee.

Drawing by Maria Lee-- basidia of 4 orders, numbered as aboveAuricularia fruiting bodies as medicine

[Largely adapted from Hobbs, Christopher, 1996. Medicinal Mushrooms: an exploration of tradition, healing, and culture. Botanica Press, Santa Cruz, CA and from Benjamin, Denis R. 1995. Mushrooms: poisons and panaceas. W.H. Freeman and Company, NY. ]

Do you think you've ever eaten Auricularia? You probably have, even without knowing it. The gelatinous rubbery texture in "hot and sour soup" is Auricularia. The fungus doesn't have much flavor on its own, but it soaks up the flavor of whatever it's cooked with. Moreover the texture is very interesting to the educated palate.

Besides its culinary value, Auricularia also has significant medicinal properties and has been used for many centuries in traditional herbal remedies. According to the Doctrine of Signatures, a theory popular in Europe in the 1800's, plants and fungi resembling certain parts of the body could be used to treat ailment of that part of the body. Since the fungus resembles the folds of the throat, Auricularia boiled in beer, milk, or vinegar was used to treat throat ailments. Because its gelatinous consistency could bind eye medicine, it was also often used as a salve to treat eye ailments.

Auricularia auricula-judae and its cousin A. polytricha have been used as medicines for many centuries in China, particularly to cure hemorrhoids and strengthen the body, perhaps by stimulating the immune system. It was also sometimes used to treat such widely varying conditions as hemoptysis (spitting up blood), angina (cardiac pain), diarrhea, and warding against gastrointestinal upset.

"Modern" medicine has yielded other secrets from Auricularia. It has been shown to block blood clotting by obstructing the platelets. There have actually been cases of internal bleeding from particularly sensitive people who accidentally ate too much sweet and sour soup combined with stir-fry containing this fungus. There is some evidence that regular ingestion of Auricularia in small doses can be therapeutic in preventing strokes and heart attacks.

Other therapeutic uses of Auricularia from modern medicine include lowering blood cholesterol and triglycerides. There is even some evidence it can play a role in treating diabetes and cancer, and some studies claim it can reverse ageing by increasing SOD activity for DNA repair. However, due to the possibility of anti-fertility effects, this fungus is not recommended for pregnant or lactating women, as well as those intending to conceive. There is also a report of a man who consumed over 250 grams of this fungus who developed a severe "solar dermatitis," making his skin very sensitive to sunlight. Although there is anecdotal information such as this, general side effects are not well documented or expected.

I hope you enjoyed learning something about Auricularia and the rest of the jelly fungi. Now you have some more interesting stories to tell your friends in the woods-- and in a Chinese restaurant!

For an additional FUN Easter activity, you can take this mycological Easter egg hunt! Start by clicking here.

If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at

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