Rhodotus palmatus

[ Basidiomycetes > Agaricales > Tricholomataceae > Rhodotus . . . ]

by Ron Meyers

For a mushroom that in many field guides is described as infrequent, it is surprising that we find Rhodotus palmatus every year in Kansas, where we are frequently rather lacking in rain, and consequently in mushrooms. The first time I discovered this mushroom, I was completely at a loss to identify it. While our Kansas mushroom guide states that “the ridges on the cap form a distinctive network which make this species unmistakable,” my specimen had absolutely no ridges. Instead it had a slightly gelatinous but smooth surface, not at all resembling the photos. What I discovered was that the mushroom must dry slightly to form the ridges, and a fresh specimen growing in wet conditions may not have this development. I have not seen this characteristic mentioned in any field guide but you can observe it in the second photo.

My other major surprise regarding this mushroom was when I discovered the cluster illustrated in the top photo. The species is described as fruiting singly or in small groups. I had usually seen it as a solitary mushroom, or growing in pairs. This was a spectacular grouping, but I have not found such a cluster since.

The edibility of Rhodotus palmatus is unknown, but it is almost too attractive to eat. Just enjoy the beautiful colors and distinctive appearance, and be satisfied that you have found a fairly rare mushroom.

Description:

Ecology: Saprobic; growing alone or in (usually) small groups on dead hardwood; reported from northeastern North America, the upper Great Lakes region, and eastern Kansas; late spring into early fall. See note below.

Cap: 3-8 cm; convex with an incurved margin when young, becoming broadly convex; surface conspicuously netted, except when very fresh and wet; reddish or salmon to pinkish.

Gills: Attached to the stem; close; whitish when young, becoming pink to salmon from spores; moderately broad and cross-veined.

Stem: 2.5 to 5 cm long, 3-6 mm thick; reddish to pink; slightly hairy; off-center to almost lateral; curved; dry; tough.

Flesh: Rubbery and gelatinous.

Taste: Mild; odor not distinctive.

Chemical Reactions: All surfaces instantly dark green with iron salts; negative with KOH (Michael Kuo).

Spore Print: Pinkish.

Microscopic Features: Spores 6-8 µ; round or vaguely elliptical; finely warted; inamyloid.

REFERENCES: (Bulliard: Fries) Maire, 1926. (Smith, Smith & Weber, 1979; Arora, 1986; Lincoff, 1992; Horn, Kay & Abel, 1993; Sundberg, Methven & Monoson, 1997 [Mycotaxon 65: 403-410].) Herb. Kuo 05280403.

This is the only species of Rhodotus known. For a number of years the Kaw Valley Mycological Society had a standing request from mycologist Orson Miller to dry and send Rhodotus palmatus specimens for him to study as they were not found in his usual foray areas, and we were a steady source of supply.

Note: In a study of Rhodotus palmatus in Illinois (Sundberg, Methven & Monoson, 1997), the authors found that the species "tends to occur on logs in or near low lying areas, such as swamps and creek or stream beds, that are periodically flooded and where the canopy is relatively closed" (407).

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Meyers, R. (2004, June). Rhodotus palmatus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/rhodotus_palmatus.html