Tricholoma terreum

Description

Tricholoma terreum is a gray-capped mushroom of the large genus Tricholoma. It is poisonous and can cause acute kidney failure because it releases a red muscle pigment that clogs the kidney ducts. The consequences can be fatal. It has many look-alikes mushrooms.

T. terreum is found in Europe and North America, where fruiting bodies appear under conifers, particularly pine and spruce, from late summer to late autumn. They may also arise in parks near these trees, and grow in fairy rings.

This mushroom was considered edible and mentioned in atlases, but in 2014 information about its toxicity appeared. The effect is cumulative, i.e. one dose usually does not cause problems until repeated ingestion. The reaction is very individual, but it is recommended to avoid this fungus.

Common names: Gray Knight, Dirty Tricholoma, Muisgrijze Ridderzwam (Netherlands), Gemeiner Erdritterling (German), Čirůvka zemní (Czech Republic).

Mushroom Identification

1. Cap

   4–7.5 cm across; at first convex with a central bump, becoming broadly bell-shaped or broadly convex; dry; finely, radially appressed-fibrillose or, with age, finely scaly; the margin usually finely woolly, especially in young specimens; gray to brownish gray.

2. Gills

   Attached to the stem by a notch; close; short-gills frequent; grayish; sometimes protected by a cortina-like veil in very young specimens.

3. Stem

   3–5 cm long; 1–1.5 cm thick; equal; bald; dry; whitish.

4. Flesh

   White; unchanging when sliced.

5. Spore Print

   White.

6. Habitat

   Mycorrhizal with conifers, pines, spruce, fir, and Douglas-fir. More rarely with hardwoods, at least in Europe. Growing alone, scattered, or gregariously, through spring till fall in Europe and North America.

7. Microscopic Features

   Spores 5–8 x 3.5–4.5 µm; ellipsoid, with a small apiculus; smooth; hyaline in KOH; inamyloid. Lamellar trama parallel. Basidia 4-sterigmate; 30–35 x 5–7 µm; clavate. Cystidia not found. Pileipellis a cutis; elements 6–15 µm wide, smooth, hyaline or brown-walled in KOH. Subpellis clearly differentiated as a layer of inflated cells 10–25 µm across. Clamp connections not found.

Look-Alikes

1. Tricholoma scalpturatum

   It is recognized by a strong farinaceous odor, and a paler fibrillose-squamulose cap.

2. Tricholoma cingulatum

   Associated species with a pale grey fibrillose cap, is distinguished by a cottony white ring.

3. Tricholoma pardinum

   A poisonous mushroom with a mealy odor.

4. Tricholoma virgatum

   The cap without scales with a pointed top. It is inedible.

5. Tricholoma argyraceum

   Has yellowing scales and narrower spores.

6. Tricholoma atrosquamosum

   Has slightly larger fruiting bodies with cap skin that splits into dark scales.

7. Tricholoma orirubens

   Grows under deciduous trees and the leaves turn pink with age.

8. Tricholoma portentosum

   Has a striking yellow-green shade on the rub and often a purplish skin on the cap.

9. Tricholoma triste

   Has a blackish finely scaly stem and is larger.

10. Tricholoma gausapatum

    Has a velvety-silky cap, usually reddish-colored, and with bluish gills.

11. Tricholoma leucoterreum

    Has pure white fruiting bodies.

History

The fungus was originally described as Agaricus terreus by Jacob Christian Schäffer in 1762, and as Agaricus myomyces by mycologist Christian Hendrik Persoon in 1794. It was given its current binomial name by German Paul Kummer in 1871.

The specific epithet terreum is Latin and means "earth", which leads us to the color of the mushroom's cap.

Synonyms and Varieties

• Agaricus terreum Schaeff. (1774)

• Agaricus madreporius Batsch 1789

• Agaricus myomyces Pers., Neues Mag. Bot. 1: 100 (1794)

• Agaricus myomyces Pers., subsp. myomyces

• Agaricus myomyces Pers., var. myomyces

• Agaricus myomyces subsp. myosinus Pers.

• Agaricus myomyces var. albescens Pers.

• Agaricus myomyces var. albogriseus Pers.

• Agaricus myomyces var. madreporius (Batsch) Pers.

• Agaricus myomyces var. myomyces-alter Fr.

• Agaricus myomyces var. rubroguttatus lasch

• Agaricus myomyces var.communis Alb. & Schwein.

• Agaricus pullus Batsch 1783

• Agaricus terreus Schaeff. 1762

• Agaricus terreus Schaeff. var. terreus

• Gymnopus myomyces (Pers.) Gray 1821

• Tricholoma bisporigerum J.E. Lange, 1933

• Tricholoma leucoterreum Mariotto & Turetta 1996

• Tricholoma myomyces (Pers.) J. E. Lange var. myomyces

• Tricholoma myomyces (Pers.) J.E. Lange 1933

• Tricholoma myomyces f. bisporigerum (J.E. Lange) Bon 1975

• Tricholoma myomyces var. cystidiotum Shanks

• Tricholoma myomyces var. myomyces (Pers.) J.E. Lange 1933

• Tricholoma terreum (Schaeff.) P. Kumm. var. terreum

• Tricholoma terreum f. argentatum (Bon) Blanco-Dios

• Tricholoma terreum f. dermatovelatum E. Ludw.

• Tricholoma terreum var. aetnense Bacc.

• Tricholoma terreum var. bisporigerum (J. E. Lange) E. Ludw.

• Tricholoma terreum var. bresadolae Sacc.

• Tricholoma terreum var. cystidiotum (Shanks) Blanco-Dios

• Tricholoma terreum var. fragrans Peck

• Tricholoma terreum var. gracilior Peck

• Tricholoma terreum var. myomyces (Pers.) Blanco-Dios

• Tricholoma terreum var. terreum (Schaeff.) Quél.

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