Amanita species 01: The Sand Dune Amanita

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by Michael Kuo

I find this Amanita in sand dunes near the coast of Lake Michigan, in Emmet County, MI. It is a very curious amanita, since it grows without any trees nearby and is apparently mycorrhizal with huckleberry bushes, which grow in abundance in the immediate vicinity. The same sand dunes often hold several well known sand-loving mushrooms, including Russula ventricosipes and Laccaria trullisata.

The "Sand Dune Amanita" has a sack-like volva and a sturdy ring. These features, together with its amyloid spores and naked cap margin, place it in section Phalloideae. According to Amanita expert Rodham Tulloss, who has examined the illustrated specimens, "the closest named species is Amanita suballiacea (Murrill) Murrill" (2004, pers. com.). However, Tulloss notes, the type collection of Amanita suballiacea is not well preserved, making comparison difficult.

I performed the Meixner Test to determine whether deadly amatoxins were present in the Sand Dune Amanita, and my results (illustrated to the right) were clearly positive.

Description:

Ecology: Apparently mycorrhizal with huckleberry, but perhaps saprobic; in back dunes about 5 miles from Lake Michigan; with Eastern White Pines at a distance of over 50 yards; Emmet County, MI; September 12, 2004.

Cap: 6 cm; convex; whitish with hints of rose; margin faintly lined; without universal veil remnants.

Gills: Free from the stem; close; with a few short-gills; white.

Stem: 20 x 1.5 cm; tapered to apex; without a basal bulb; white to off-white; terminating in a sack-like, whitish, fairly adherent volva; with a high, skirtlike ring.

Flesh: White.

Odor: Rancid--but the specimen was clearly past maturity.

Chemical Reactions: KOH on cap surface yellow.

Spore Print: Presumably white.

Microscopic Features: Spores 9-11 x 7-9 µ; broadly elliptical; smooth; amyloid. Tulloss's measurements (2004, pers. com.), much more finely tuned than mine, are as follows: "(8.6-) 8.9 - 10.9 (-12.8) x (7.0-) 7.2 - 8.5 (-9.1) µ, (avg. length = 10.0 µm; avg. width = 7.8 µm); Q = (1.11-) 1.18 - 1.40 (-1.45); avg. Q = 1.28)."

REFERENCES: Herb. Kuo 09120413, 09110511.

Results of the Meixner Test on the Sand Dune Amanita (in the middle).

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Cite this page as:

Kuo, M. (2004, November). Amanita sp. 01: The sand dune amanita. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_sp_01.html