Amanita jacksonii

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

by Michael Kuo

The North American versions of Amanita caesarea, the infamous mushroom that was (by tradition, anyway) a favored delicacy of Roman emperors, are numerous and confusing, and their taxonomy has not yet been completely established. The principal (mushroom) players in this drama are fairly easily recognized by their yellow gills, their large, white, sacklike volvas, and their bright orange or orange red caps, which have lined margins. Heading up the cast (for the taxonomical moment, anyway) is Amanita jacksonii. It is an impressive eastern actor, appearing in woodland theaters from the province of Quebec to the state of Hidalgo, and recognized by its brilliant colors, the slender yellow stem with reddish to orange fibers, the fact that the cap begins to fade to yellow from the margin inward, and microscopic features.

Amanita jacksonii is described below; comments on other characters in the "Slender Caesar" drama follow.

Do not eat these or any other Amanitas!

Description:

Ecology: Mycorrhizal with oaks and pines; summer and fall; widely distributed east of the Great Plains, from Quebec to Hidalgo.

Cap: 8-12 cm; oval at first, becoming convex, typically with a central bump; sticky; brilliant red or orange, fading to yellow on the margin; typically without warts or patches; the margin lined for about 40-50% of the cap's radius.

Gills: Free from the stem or slightly attached to it; yellow to orange-yellow; crowded; not bruising.

Stem: 9-14 cm long; 1-1.5 cm thick; slightly tapering to apex; yellow; with orange to reddish fibers, often in zones; not bruising; with a yellow to orange, skirtlike ring; with a large (4-7 cm high and 4 mm thick) sacklike volva.

Flesh: Whitish to pale yellow; not staining on exposure.

Spore Print: White.

Microscopic Features: Spores 7-10 µ long; broadly elliptical; smooth; inamyloid.

REFERENCES: Pomerleau, 1984. (Tulloss, 2006; Roody, 2003; McNeil, 2006; Tulloss, 2007.) Herb. Kuo 10200704.

Amanita tullossii and Amanita umbonata are synonyms.

Further Online Information:

Amanita jacksonii at Tulloss's Studies in Amanita
Amanita caesarea at Roger's Mushrooms

Dramatis Personae

Field guides are likely to include blanket treatments of "Amanita caesarea," a European species first described by Fries and later redefined by others. Whether or not the "true" Amanita caesarea occurs in North America is uncertain. A robust species common under ponderosa pine in Arizona and New Mexico has been "passing" as Amanita caesarea for years; it has a stem 1.5-3 cm thick (see description and photos in Arora, 1986).

Most of the North American versions of Amanita caesarea, however, have slender stems and are sometimes refered to as the "slender Caesars." Worldwide, the slender Caesars form a bewildering cast of characters, many of which have been described but not officially published as yet. In North America, the stage is only slightly less crowded:

Amanita arkansana, found under pine and oak in the southeastern United States, is orange-brown to yellowish, has a paler stem than Amanita jacksonii, and has gills that soon fade from yellow to nearly white. Its volva clings tightly to the stem.

A possibly unnamed Amanita species, similar to Amanita jacksonii, is depicted and briefly described by Phillips (1991), collected in New Jersey. It may or may not be the same mushroom described below as Amanita banningiana (Tulloss nom. prov.). Its cap is brownish in the center and yellowish towards the margin, and its stem is white. Phillips's longer entry, for what he calls the "American Caesar's Mushroom" in a rather delightful instance of misplaced modification, probably depicts Amanita jacksonii, though he has used "Amanita caesarea" as a name, with a caution that "[t]here is much dispute about the name that should be given to this mushroom" (17).

Amanita murrilliana, found east of the Great Plains under oak or in mixed birch-conifer woods, differs from Amanita jacksonii by having much paler colors, and a volva that is broadly attached to the stem.

Amanita banningiana (Tulloss nom. prov.) has a cap that is yellow at first, becoming yellowish brown to orange-brown in the center; it is found in beech/oak or pine/oak forests, and has spores 8.5-12 µ long.

"Amanita sp. F10," a Florida species growing in pine/oak woods, has a bright yellow cap that is reddish orange in the center and spores 9-11 µ long.

"Amanita sp. CR6," a Central American oak lover, has a cap that demonstrates olive shades when young, and is later brownish yellow with a reddish brown center; its stem has dirty yellow remnants of the universal veil clinging to it, and its spores are 8-11 µ long.

Several Mexican Caesars have been described by Guzman & Ramirez-Guillen (2001), including Amanita basii, Amanita laurae and Amanita yema, all of which have thick stems like the European Amanita caesarea.

Cite this page as:

Kuo, M. (2008, March). Amanita jacksonii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_jacksonii.html

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