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Amanita species 05: Barrows's Amanita

by Michael Kuo, 6 January 2023

Here is a fascinating, aspen-loving, ring-less Amanita from Colorado and New Mexico. It is similar to Amanita populiphila, but features a more deeply colored cap and a much more sturdy, sack-like volva. The brassy orange cap is only slightly lined at the margin, and the volva often features orangish hues on its inner surface.

Although this species has no official name, it was apparently on mycological giant Alexander Smith's "to-do" list; in a never published manuscript Smith planned to honor New Mexico's legendary amateur mycologist, Chuck Barrows, who knew the unnamed Amanita well and sent several collections to Smith for study.

Thanks to the Herbarium of the Field Museum of Natural History for facilitating study of the collection cited and described below. Thanks to Hoa Pham for documenting, collecting, and preserving Amanita species 05 for study; her collection is deposited in The Herbarium of Michael Kuo.


Ecology: Mycorrhizal with quaking aspen; growing alone, scattered, or gregariously; July and August; Arizona, Colorado, and New Mexico. The illustrated and described collections are from Colorado.

Cap: 3–10 cm across; bell-shaped to convex, becoming planoconvex—often with a broadly conical center; bald; sticky when fresh; orange to dull brassy orange, pinkish orange, or brownish orange, fading to dull orangish; rarely with a whitish patch; the margin sometimes slightly lined at maturity.

Gills: Free from the stem or nearly so; close; whitish; sometimes with orangish edges; with frequent short-gills.

Stem: 5–15 x 0.5–1.5 cm; tapered slightly to the apex; without a ring; dirty whitish; bald or with stretched-out fibrils that sometimes become arranged in vague stripes or zones; with a sturdy, thick, white, sacklike volva that usually extends one-fourth to one-half the length of the stem and often features an orangish inner edge.

Flesh: White; unchanging when sliced.

Odor: Not distinctive.

Spore Print: White.

Microscopic Features: Spores 7–9 x 8–10 µm; globose or subglobose, with a prominent apiculus; smooth; hyaline in KOH; amyloid. Basidia 38–44 x 8–12 µm; clavate; 4-sterigmate; clamps not found. Hymenial cystidia not found.

REFERENCES: (A. H. Smith [unpublished manuscript]; Tulloss, 2013.) Herb. F NAMA 2010-160. Herb. Kuo 08312202.

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Amanita species 05

Amanita species 05

Amanita species 05

Amanita species 05

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Kuo, M. (2023, January). Amanita sp. 05: Barrows's Amanita. Retrieved from the MushroomExpert.Com Web site: