Amanita thiersii

[ Basidiomycetes > Agaricales > Amanitaceae > Amanita . . . ]

by Ron Meyers

This mushroom’s large size, white color, and the unusual sticky, shaggy remnants of the universal veil covering virtually the entire fruiting body make it easy to identify. For those who appreciate mushrooms for their beauty, this is a very welcome sight in a green lawn. It is not a pleasure to collect, however, as it is impossible to pick without depositing the sticky tissue on your hands, clothing, and any other surface it touches.

The edibility of Amanita thiersii is unknown (see note below), but it is certainly not recommended. Closely related species are reportedly poisonous. It is an unusual Amanita in that, so far as can be determined, it does not associate with any kind of tree. It is strictly a lawn mushroom.

Description:

Ecology: Apparently saprobic. Originally described from Texas, it has since been found in Kansas, Missouri, and Illinois. While it frequently forms large fairy rings in lawns, pastures, and prairie in hot, wet summer weather, it will also fruit as isolated specimens.

Cap: 7-20 cm broad, oval becoming convex, white, covered with sticky, shaggy universal veil material, especially when young.

Gills: Free from stem, white to pale yellow.

Stem: 8-20 cm long, 1-1.25 cm thick, white, shaggy, sticky, slightly bulbous. The ring is white and membranous, and the volva is inconspicuous.

Flesh: White, firm.

Spore Print: White.

Microscopic Features: Spores 7.5-9.5 x 7-9 µ; smooth; round to broadly elliptical; amyloid.

REFERENCES: Bas, 1969. (Smith, Smith & Weber, 1979; Weber & Smith, 1985; Jenkins, 1986; Metzler & Metzler, 1992; Horn, Kay, & Abel, 1993.) Herb. Kuo 07280307, 07290301, 07220704.

In 1978 Skip and Sherry Kay (future founders of the Kaw Valley Mycological Association) first noted a very unusual Amanita growing in the older part of the city of Lawrence, Kansas. They were unable to identify it, even with the help of a professional mycologist. In 1986 they noted a resemblance to Amanita praegraveolens, described in David T. Jenkins's Amanita of North America. However, this description mentioned a sickly smell and a pinkish color, which their Amanita did not possess, and made no mention of the sticky tissue covering the mushroom.

The mystery was finally solved in 1988 with the study of Nancy Smith Weber and Alexander H. Smith’s A Field Guide to Southern Mushrooms. The description for Amanita thiersii, named in honor of Dr. Harry Thiers, fit the mushroom perfectly. The big surprise and impediment to earlier identification was that it was indeed considered a southern mushroom, and northern Kansas was certainly not part of the south.

Amanita thiersii has evolved from a rare find to a common summer lawn mushroom in Lawrence. It is a large mushroom, and very beautiful with the sticky cottony remains of its universal veil covering both the cap and stalk. It may often be found fruiting in the same lawn with Chlorophyllum molybdites.

[Note: Amanita expert Rodham E. Tulloss (2003, Pers. Com.) suspects that A. thiersii contains kidney toxins like those in A. smithiana. Further research may confirm A. thiersii as a deadly poisonous species. (M. Kuo)]

Further Online Information:

Amanita thiersii at Rodham Tulloss's Studies in Amanita

Specimen with a smooth cap, after heavy rains.

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Cite this page as:

Meyers, R. (2003, March). Amanita thiersii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_thiersii.html