What You Should Know
Leratiomyces ceres are mushroom which has a bright red to orange cap and dark purple-brown spore deposit. It is usually found growing gregariously on wood chips and is one of the most common and most distinctive mushrooms found in that habitat.
Despite an attractive appearance, this inedible species is likely to cause an upset stomach if it is eaten. The very similar Leratiomyces squamosus is known to contain hallucinogenic psilocybin/psilocin.
Previously this mushroom was called "Stropharia aurantiaca" until DNA studies began to break up the stropharioid mushrooms. A 2008 paper by Bridge and collaborators finds support for two clearly defined groups within what used to be called "Stropharia": the Stropharia group (containing Leratiomyces squamosus, Leratiomyces percevalii, Leratiomyces magnivelaris, and species of Weraroa).
Other names: Redlead Roundhead.
Leratiomyces ceres Mushroom Identification
Saprobic; growing scattered or gregariously in woodchips or sawdust, lawns, gardens, and so on; fall through spring; coastal California to British Columbia.
2–6.5 cm; convex, becoming broadly convex, broadly bell-shaped, or nearly flat; bald; sticky when fresh, but soon dry; reddish-orange to brownish orange; when young adorned with white veil remnants along the margin; the margin not lined.
Attached to the stem by a notch; close; short-gills frequent; pale yellow at first, later purplish gray to purple-black; with whitish to pale yellow edges when mature; sometimes developing reddish stains and spots.
3–5 cm long; up to 1 cm thick; equal; dry; with or without a ring zone; bald or finely hairy; whitish to yellowish, staining reddish-orange with maturity; base often with whitish to yellowish mycelial threads; basal mycelium white.
Whitish; unchanging when sliced.
Odor and Taste
KOH on cap surface dark gray.
Spores 10–14 x 6–8 µm; ellipsoid; with a large (1 µm) pore at one end; smooth; brown in KOH. Basidia 4-sterigmate. Cheilocystidia as leptocystidia; 25–40 x 5–7.5 µm; cylindric-flexuous to fusiform or somewhat irregular; smooth; thin-walled; hyaline or golden in KOH. Pleuro-chrysocystidia 35–50 x 10–15 µm; lageniform; thin-walled; smooth; hyaline, with a globular, yellowish-refractive inclusion in KOH; sometimes absent. Pileipellis a thin ixocutis of cylindric elements 5–10 µm wide, golden in KOH, smooth, clamped at septa; over a cellular subpellis.
Leratiomyces ceres Look-Alikes
Include L. squamosus, Agrocybe putaminum, Tubaria furfuracea.
In psilocybin mushroom hunting communities in Australia and New Zealand, L. ceres (or "Larrys" as commonly nicknamed) are scorned as lookalikes and imposters of Psilocybe species on the wood chip. Prolific growth in the same habitats and a similar appearance from afar can give false hope of a large bounty, but on closer inspection, the species are not particularly alike.
The Bloodred Webcap, Cortinarius sanguineus, has a red cap but its gills are initially bright red and become a rusty reddish-brown at maturity; its spore print is rusty brown rather than purple-brown.
Leratiomyces ceres Taxonomy and Etymology
When in 1888 British mycologists Mordecai Cubitt Cooke and George Edward Massee (1850 - 1917) described this species, they gave it the binomial scientific name Agaricus ceres.
In 2008 Brian Spooner and colleagues established the currently-accepted scientific name of this mushroom as Leratiomyces ceres.
Synonyms of Leratiomyces ceres include Stropharia aurantiaca, by which this species is still most commonly known, as well as Hypholoma aurantiaca, Psilocybe aurantiaca, Psilocybe ceres, Naematoloma rubrococcineum and its basionym Agaricus ceres Cooke & Massee.
This genus name originated in 1907 when Narcisse Théophile Patouillard created the name Le Ratia (which he applied to a puffball fungus) in honor of French botanist and plant collector Auguste-Joseph Le Rat (1872 - 1910), who on various occasions had provided Patouillard with fungal specimens that he had collected. From this origin, Spooner and colleagues derived the new genus name Leratiomyces.
The specific epithet ceres is a reference to the cherry red color of caps.
Photo 1 - Author: Bernard Spragg. NZ from Christchurch, New Zealand (Public Domain)
Photo 2 - Author: Hamilton (ham) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Richard Daniel (RichardDaniel) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 4 - Author: michæl (Creative Commons Attribution 4.0 International)
Photo 5 - Author: michæl (Creative Commons Attribution 4.0 International)