Entoloma abortivum

[Basidiomycetes > Agaricales > Entolomataceae > Entoloma . . . ]

by Michael Kuo

Entoloma abortivum is either one of the most distinctive mushrooms one can find, or one of the harder ones to identify--depending on whether you can find it exhibiting both its Dr. Jeckyll and its Mr. Hyde masks.

Dr. Jeckyll is a steely gray, pink-spored, gilled mushroom with a cap that is at first convex with an inrolled margin, and later more or less flat. The gills are usually at least partially "decurrent," meaning they run down the stem. But there is a whole HMO full of Dr. Jeckyll look-alikes, known as Entoloma Care Systems, Incorporated. Mr. Hyde, on the other hand, is a glob of pale fungal flesh that looks like a malformed puffball. When sliced open, the glob has pinkish areas or veins inside.

For over a hundred years it was believed that the Mr. Hyde form represented an "aborted" form of Dr. Jeckyll, an Entoloma that never happened--as the species name suggests. In the seventies, however, mycologists suggested that Mr. Hyde might result from parasitizing action on the part of the mycelium of Armillaria mellea. But recent research has turned this idea on its head, suggesting that Entoloma abortivum is the parasite, and Armillaria mellea the victim! See the comments below for the whole story.

Description:

Ecology: Parasitic on species of Armillaria, and perhaps also saprobic, growing scattered or gregariously near decaying wood, or in leaf litter near decaying wood; usually encountered with Armillaria species fruiting in the vicinity; late summer and fall; widely distributed east of the Rocky Mountains.

Cap: 4-10 cm; convex with an inrolled margin, expanding to flat, broadly convex, or with a central bump; fairly smooth, or with appressed fibers; dry; gray to grayish brown.

Gills: Attached to the stem or beginning to run down it; close or crowded; pale grayish at first, later becoming pink from maturing spores.

Stem: 3-10 cm long; .5-2 cm thick; occasionally somewhat off-center; typically with an enlarged base; solid; smooth or finely hairy; with white basal mycelium and threads.

Flesh: Thick; white.

Odor and Taste: Mealy.

Spore Print: Pink.

Microscopic Features: Spores 7-9 x 6.5-8 µ; angular and irregular; 5- to 8--sided. Cystidia absent. Pileipellis an ixocutis. Clamp connections present.

"Aborted" Form: An irregular ball of tissue 2-10 cm high; white; with pinkish areas inside; microscopically containing hyphae from Entoloma abortivum and Armillaria species.

REFERENCES: (Berkeley & M. A. Curtis, 1859) Donk, 1949. (Hesler, 1967; Smith, Smith & Weber, 1979; Noordeloos, 1980; Weber & Smith, 1985; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Barron, 1999; Roody, 2003; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 10090302.

Will the Real Parasite Please Stand Up?

Over a hundred years ago, Charles Peck (1893; see Czederpiltz, Volk & Burdsall, below) reported finding Armillaria mushrooms curiously "aborted" like specimens of Entoloma abortivum. In fact, Peck found these aborted Armillaria specimens to be "in no way distinguishable" from aborted forms of Entoloma abortivum. Over the years, others noted aborted, Entoloma abortivum-like forms of Armillaria species--and who knows how many collectors noticed that Entoloma abortivum tended to fruit in the vicinity of Armillaria species--but it apparently occurred to no one that there might be a relationship between the two mushrooms.

In 1974, Watling studied "aborted" Entoloma abortivum specimens and discovered that Armillaria mellea cells were present in the tissues. He concluded that Armillaria mellea parasitizes Entoloma abortivum. Though Watling did not scientifically prove this idea, "[t]he hypothesis that Armillaria could be a mycoparasite seemed plausible to many mycologists because Armillaria is a notorious pathogen of a wide variety of gymnosperms and angiosperms" (Czederpiltz, Volk & Burdsall, 842).

Field guide treatments of the "Aborted Entoloma" published after Watling's discovery accept the hypothesis that Armillaria species attack Entoloma abortivum. However, a study in 2001 by Czederpiltz, Volk & Burdsall found the exact opposite to be true. Using culture studies and field observations, these mycologists suggest that "Aborted Entoloma" fruitings "represent malformed Armillaria fruiting bodies permeated by E. abortivum hyphae," and recommend the use of the common name "Abortive Entoloma" to indicate the aggressive, rather than passive, role played by Entoloma abortivum.

Source: Czederpiltz, D. L., Volk, T. J. & H. H. Burdsall, Jr. (2001). Field observations and inoculation experiments to determine the nature of the carpophoroids associated with Entoloma abortivum and Armillaria. Mycologia 93: 841-851.

Below: Entoloma abortivum attacking Armillaria mellea.

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Cite this page as:

Kuo, M. (2003, October). Entoloma abortivum. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/entoloma_abortivum.html