Calocybe gambosa

Calocybe_gambosa.jpg
St. George's mushroom, Calocybe gambosa.
  Credit: Jean-Jacques Wuilbaut
  Source: French Wikipedia

Classification
 
Kingdom Fungi
Phylum Basidiomycota
Class Basidiomycetes
Order Agaricales
Family Tricholomataceae
Genus Calocybe

Synonyms

Agaricus albellus DC.
Agaricus aromaticus Roques
Agaricus gambosus Fr.
Agaricus georgii L.
Calocybe gambosa (Fr.) Singer [as 'gambosum']
Calocybe georgii var. aromatica (Roques) Pilát
Calocybe georgii var. gambosa (Fr.) Kalamees
Lyophyllum gambosum (Fr.) Singer
Tricholoma gambosum (Fr.) Gillet
Tricholoma georgii (L. ex Hook.) Quél.

Common Name

St. George's mushroom
See this link for an impressive list of common names in various languages.

Description

Cap: at first whitish-cream, when old it turns orange-yellow to yellowish-brown; smooth, bare and dry. The cap of the young mushroom is a rounded cone or bell shape; later it becomes convex and when old planar;  5–15 cm in diameter.
Gills: initially white to cream; then pale orange-yellow; 5-10 mm wide, crowded, narrow, almost always notched where they join the stipe. The margin of the gills later becomes toothed and torn.
Stem: first club-shaped, then cylindrical; 4-8 cm long, 1.5-3.0 cm thick, whitish or pale cream; its base is usually orange-yellow or rust. Its surface is streaked with fibers; immediately under the cap the stipe may be slightly scaly.
Flesh: white, firm, does not change its color when cut, tastes pleasant and smells like freshly ground flour.
Smell: mealy.
Spore deposit: white.
Spores: 5–7 x 3–4 µm, hyaline, ovoid or compact ellipse; smooth; colorless.
Habitat: grows from the end of April to the beginning of June, especially in meadows, pastures, on the edges of deciduous woods. In mountain regions with harsher climates it arrives later, from the beginning of June to the first half of July. It can be found alone or in small clumps, also in circles.

The English common name refers to the fact that these mushrooms usually appear around the Saint's day of April 23rd, although it frequently matures around a week later.

Medicinal properties
Antibacterial activity

A dichloromethane extract of Calocybe gambosa was shown to be antibacterial towards Bacillus subtilis and Escherichia coli (Keller et al., 2002).

Blood sugar reduction

The title of the Brachvogel reference (1986) suggests that the St. George's mushroom has the ability to reduce blood sugar levels, but I haven't yet seen this German paper.

References

Brachvogel, R.
[Reduction of blood sugar by Calocybe gambosa Fr. Donk.]
Zeitschrift für Mykologie. 1986 52(2):445. German.

Clemencon, H.
Phenoxazones in cultures of species of Calocybe agaricales.
Proceedings of the International Botanical Congress. 1981 13:160.

Filippi, I.
Observations of Clitocybe geotropa and Calocybe gambosa Biology.
Micologia Italiana. 1983 12(2):22-4.

Keller, C, Maillard, M, Keller, J, Hostettmann, K.
Screening of European fungi for antibacterial, antifungal, larvicidal, molluscicidal, antioxidant and free-radical scavenging activities and subsequent isolation of bioactive compounds.
Pharmaceutical Biology. 2002 40(7):518-25.

Kuchen A, Schlunegger UP.
[Products of  fungi .2. oxygen and sulfur-containing phenoxazin derivatives in Calocybe gambosa].
Archiv der Pharmazie 1988 321(6):363-5.

Schlunegger UP, Kuchen A, Clemencon H.
[Mycelium products in higher fungi. i. phenoxazine derivatives in Calocybe gambosa (author's transl)]
Helv Chim Acta. 1976 59(4):1383-8. German. No abstract available.
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Last modified: 15-Aug-2008

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