Catathelasma imperiale

The imperial cap, Catathelasma imperiale (Fr.) Singer.


Agaricus imperialis Fr.
Armillaria imperialis (Fr.) Quél.
Biannularia imperialis (Fr.) Beck
  Pilz- und Kräuterfreund 5(5-8): 231 (1922)
Catathelasma imperialis

Common names

Imperial cap


Cap: 10-40 cm diameter; convex to obtuse, expanding to flat or humped; margin incurved initially; surface viscid when young, later dry and cracking; yellowish-brown to olive brown initially, darkening and becoming more grayish brown with age; flesh thick and tapering gradually to margin, hard, white.
Gills: decurrent, initially narrow, often forked, dingy yellowish to pale olive-gray.
Stem: 12-18 long x 5-8 cm thick, rooting with a tapered base, sheathed with a dingy yellowish brown veil which forms a double ring; upper ring membranous and streaked on upper surface, lower ring gelatinous.
Spore print: white.
Spores: smooth, amyloid, subfusoid to subcylindric, 11-15 x 4-6 µm.
Habitat: solitary to scattered on soil in coniferous forests; late summer and fall.
Odor and taste: strongly farinaceous.
Edibility: edible.

Description adapted from McKnight et al., 1998, p. 137.

Bioactive compounds

Eight ergostane-type sterols and three of their derivatives (one mono-linoleate and two mono-glucosides), were isolated from the ethyl acetate soluble fraction of Catathelasma imperiale (Yang et al., 2003). Two of the sterols were previously unknown:  22E, 24R-ergosta-7, 22-diene-3β, 5α-diol-6β-linoleate and 22E, 24R-ergosta-7, 22-diene-3β, 5β, 6α-triol. These compounds have an uncommon cis-fused A/B ring.

Medicinal properties

Antitumor effects

Polysaccharides extracted from the mycelial culture of C. imperiale and administered intraperitoneally into white mice at a dosage of 300 mg/kg inhibited the growth of both Sarcoma 180 and Ehrlich solid cancers by 90% (Ohtsuka et al., 1973).

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Mushroom Expert
C. imperiale on a 1997 Slovak postage stamp


Hutchion LJ.
Host range geographical distribution and probable ecological status of Catathelasma imperiale in North America.
Mycologia. 1992 84(3):472-5.
JSTOR preview

McKnight KH, McKnight VB, Peterson T. 1998.
A Field Guide to Mushrooms: North America.
HMCo Field Guides. 448 pp.

Ohtsuka S, Ueno S, Yoshikumi C, Hirose F, Ohmura Y, Wada T, Fujii T, Takahashi E.
Polysaccharides having an anticarcinogenic effect and a method of producing them from species of Basidiomycetes.
UK Patent 1331513, 26 September 1973.

Yang SP, Xu J, Yue JM.
Sterols from the fungus Catathelasma imperiale.
Chinese J Chem. 2003 21(10):1390-4.

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