Lepiota caerulescens

[ Basidiomycetes > Agaricales > Agaricaceae > Lepiota . . . ]

by Michael Kuo

A few rare species of Lepiota demonstrate dramatic blue to green staining when handled or dried; among them, Lepiota caerulescens (which may be the same thing as Lepiota virescens) is distinct in having white flesh and gills. Lepiota viridiflavoides, described from Florida, also bruises blue, but has yellow gills and flesh.

The illustrated collection was made in Texas by mushroom expert Jay Justice. The little mushroom appeared to be one of a gazillion little Lepiota species best sorted out with microscopic analysis, until it began to bruise pinkish and reddish. Then Jay and I watched in amazement as it began to turn blue--first on the stem, then the cap, and finally, when placed in a dryer, nearly overall.

Edibility is not known for Lepiota caerulescens. For those who associate blue bruising with hallucinogenic mushrooms, its psychoactive properties are also unknown. It would make a very dangerous experiment, since some species of Lepiota are known to contain fatal toxins.

Description:

Ecology: Uncertain. Probably saprobic; originally described from Ohio (with precise ecology unspecified). The illustrated collection was made in October in Texas, in mixed woods dominated by Loblolly Pine, Willow Oak, and Sweetgum.

Cap: 1-2 cm; convex, broadly convex, or planoconvex, with a central bump; dry; smooth and brown to reddish brown over the center; elsewhere finely radially scaly with brown to reddish brown scales and fibers over a whitish ground color; the margin lined; bruising pinkish, then blue.

Gills: Free from the stem; white; close; bruising pinkish, then blue.

Stem: 3-5 cm long; up to 2 mm thick; more or less equal, with or without a small basal bulb; smooth; whitish, bruising pinkish to reddish on handling, then turning blue; with a persistent but fragile ring.

Flesh: White.

Odor and Taste: Odor not distinctive; taste not documented.

Spore Print: White.

Dried Specimens: Becoming deep blue overall while drying, then fading to brownish over time in the herbarium.

Microscopic Features: Spores 7-9 x 4-5 µ; smooth; more or less elliptical, but somewhat variable in shape (often inequilateral or slightly ovate); apiculus prominent. Cheilocystidia clavate to fat-cylindric; to about 40 x 10 µ. Pileipellis (scalp-section the disc) of long, erect, septate units with cylindric to clavate terminal elements 7.5-12 µ wide; occasionally finely encrusted. Clamp connections absent.

REFERENCES: Peck, 1899. (Saccardo, 1902; Morgan, 1906; Kauffman, 1924; Smith, Smith & Weber, 1979.) Herb. Kuo 10200707.

Lepiota virescens may be the same mushroom. It was originally described from Argentina as Lepiota erythrella var. virescens by Spegazzini. I have not seen the original description, but Saccardo's 1902 reiteration relays a mushroom very similar to Lepiota caerulescens, with spores 8-11 x 4-5 µ--somewhat longer than the "7 µ" cited by Peck (see the right-hand column). Morgan (1906) synonymizes Peck's caerulescens with Spegazzini's erythrella var. virescens, promoting it to the rank of species (Lepiota virescens) and citing the spores as "7-9 x 4-5 mic." Both virescens and caerulescens were coined in 1899; if the names are in fact synonymous the correct name would depend on which publication, Peck's or Spegazzini's, preceded the other. The Index Fungorum lists both caerulescens and virescens as valid species names.

Smith, Smith & Weber (1979) describe Lepiota caerulescens, adding several microscopic details to the record; they appear to have collected it or studied the collections of others, though I find no mention of it in Helen Smith's Lepiota publications (including her 1966 study of Lepiota type collections). However, the 1979 description is peppered with probable typographical errors ("gills distant, moderately crowded" and "spores 7-9 x 4-3.5 µm"), and should probably be viewed as suspect.

Two species, Lepiota cyanescens of Africa and Lepiota viriditincta of Sri Lanka, are apparently similar, according to Akers and collaborators (2000); I have not seen descriptions of these mushrooms. Other blue-bruising Lepiota species have yellow flesh and gills, including Lepiota viridiflavoides of Florida and, apparently, this 1973 collection from the Tulane University campus in Louisiana, identified as "Lepiota caerulescens" by L. R. Hesler but described by the collector as "[y]ellow, turning blue."

Dried specimen

Spores

Pileipellis

Lepiota coerulescens [sic]

Peck's original 1899 description is:

   "Pileus thin, convex, obtuse or slightly umbonate, squamulose, whitish, the squamules and the center brownish, flesh and surface of the pileus becoming blue in drying; lamellae thin, close, free, white, becoming blue in drying; stem slender, equal, brownish, annulate, the annulus membranous, persistent, externally tinged with blue when dry; spores elliptic, 7 µ long, 5 µ broad.
   "Pileus 1.5-2 cm. broad; stem 3-5 cm. long, 2 mm. thick.
   "Ohio. C. G. Lloyd.
   "The species is closely allied to Lepiota cristata, from which it is easily separated by its assuming blue tints in drying."

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Cite this page as:

Kuo, M. (2007, October). Lepiota caerulescens. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/lepiota_caerulescens.html