Amanita gemmata species group

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by Michael Kuo

A lot of North American mushrooms are labeled "Amanita gemmata" by mushroom identifiers, and it is unclear whether any of them actually matches the European species first described by Swedish mycologist Elias Fries in 1838. Most North American Amanita experts treat our versions of the species as a group in need of further study. Since "Amanita gemmata" is reported from hardwood forests in the southeast and conifer woods in the Pacific Northwest (and just about everywhere in between), it indeed seems likely that DNA studies may eventually separate several species, since amanitas are mycorrhizal and presumably evolved with their mycorrhizal partners.

Despite being so taxonomically confusing, Amanita gemmata makes for a fairly easily recognized group of (potential) species. The fresh cap is a dull but attractive shade of yellow, and is usually moist or sticky. White warts adorn the cap surface, but they are usually flimsy and easily washed away by rain; they even seem as though they might easily slide off the wet cap surface with no more than gravity to encourage them. The stem features a flimsy, easily-lost ring and, at its base, a flimsy white volva that usually forms a small, free rim.

I have only found what I would call "Amanita gemmata" in western North America (in California and Colorado); my eastern gemmata-like collections differ on several characters, and appear to match Amanita russuloides (see the linked page for a discussion of differences). An eastern gemmata-like taxon that lacks a ring has been given the provisional name of Amanita praecox Lamoureaux; it has also been called "species 32" by Tulloss (see 2007).

Description:

Ecology: Mycorrhizal with various hardwoods and conifers; summer and fall (fall and winter in California); widely distributed (as a species cluster) in North America. Largent & collaborators (1980) document mycorrhizal association of Amanita gemmata with manzanita and lodgepole pine.

Cap: 3-11 cm; convex to planoconvex or flat; dull yellow; sticky when fresh; when young covered with white warts that are easily lost; the margin usually fairly strongly lined by maturity.

Gills: Free from the stem; close or crowded; whitish; with frequent short-gills.

Stem: 4-15 cm long; up to 2 cm thick; tapering slightly to the apex; with a small basal bulb; smooth or finely hairy; white; with a fragile white ring that is easily lost; with a white volva that typically clings tightly to the bulb and extends for a centimeter or so, but may fragment into soft patches or warts at the top of the bulb.

Flesh: White; unchanging when sliced.

Odor: Not distinctive.

Spore Print: White.

Chemical Reactions: KOH negative on cap surface.

Microscopic Features: Spores 8-11.5 x 6-9 µ; broadly elliptical; smooth; inamyloid.

Amanita junquillea is a synonym, according to many mycologists.

REFERENCES: (Fries, 1838) Bertillon, 1866. (Saccardo, 1887; Smith, Smith & Weber, 1979; Largent & collaborators, 1980; Thiers, 1982; Weber & Smith, 1985; Arora, 1986; Jenkins, 1986; States, 1990; Lincoff, 1992; Lindgren, 1998; Barron, 1999; Tulloss, 2005; Miller & Miller, 2006.) Herb. Kuo 01150601, 08160712.

Further Online Information:

Amanita gemmata at Tulloss's Studies in Amanita
Amanita gemmata at Roger's Mushrooms
Amanita gemmata at Fungi of Poland

Sweden

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Cite this page as:

Kuo, M. (2006, March). Amanita gemmata species group. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_gemmata.html