Tricholoma virgatum

Description

Tricholoma virgatum is a mushroom of the agaric genus Tricholoma. It is characterized by its small-medium size, dry, silvery gray, somewhat shiny, streaky-fibrillose, pointed conical cap, very peppery or bitter taste, and growth with conifers.

The radially streaky (virgate) nature of the cap surface sets it apart from most of the small to medium gray tricholomas, as they tend to have scaly caps. It is found in the deciduous and coniferous forests of Europe and North America.

This mushroom is inedible, speculated to be poisonous, and has a bitter and peppery taste and musty odor.

Common names: Ashen Knight, Silver Streaks, Fibril Trich, Streaked Trich, Fibril Tricholoma.

Mushroom Identification

1. Ecology

   Mycorrhizal with conifers; growing alone, scattered or gregariously; fall (and overwinter on the West Coast); fairly widely distributed in North America.

2. Cap

   2–8 cm; sharply conic when young, becoming broadly conic, or nearly flat with a sharp central bump; dry; gray; with a darker gray, innate to appressed, radiating fibrils and streaks.

3. Gills

   Attached to the stem by a notch; close; whitish to dull grayish; sometimes discoloring gray on the edges.

4. Stem

   6-10 cm long; 1-2 cm thick; equal or somewhat swollen below; with silky appressed fibers; dry; white.

5. Flesh

   Firm; white to pale grayish; not changing on exposure.

6. Odor and Taste

   Odor not distinctive; taste usually bitter or acrid (sometimes slowly).

7. Spore Print

   White.

8. Chemical Reactions

   KOH on cap surface dull orangish; on stem base pale yellow.

9. Microscopic Features

   Spores 7–9 x 4–6 µm; broadly ellipsoid; smooth; hyaline in KOH; inamyloid. Pleurocystidia absent. Cheilocystidia basidiole-like. Pileipellis a cutis of cylindric elements 2–7.5 µm wide. Clamp connections absent.

Tricholoma virgatum Look-Alikes

1. Tricholoma sciodes

   Has pinkish to violaceous tones, less pointed cap, bitter but not peppery taste, and growth with beech and perhaps other broad-leaved trees.

2. Tricholoma terreum

   Occurs under deciduous trees on alkaline soil; it is almost odorless.

History

This mushroom was first described scientifically in 1818 by the great Swedish mycologist Elias Magnus Fries, who named it Agaricus virgatus.

German mycologist Paul Kummer transferred this and several other 'knights' to the genus Tricholoma in 1871.

Synonynms of Tricholoma virgatum include Agaricus virgatus Fr., Agaricus fumosus subsp. virgatus (Fr.) Pers., and Gyrophila virgata (Fr.) Quél.

Tricholoma was established as a genus by the great Swedish mycologist Elias Magnus Fries. The generic name comes from Greek words meaning 'hairy fringe', and it must be one of the least appropriate mycological genus names because very few species within this genus have hairy or even shaggily scaly cap margins that would justify the descriptive term.

The specific epithet virgatum is Latin and means streaked or striped - a reference to the radial streaks on the cap.

Photo sources:

Photo 1 - Author: Ron Pastorino (Ronpast) (CC BY-SA 3.0)

Photo 2 - Author: Jerzy Opioła (CC BY-SA 4.0)

Photo 3 - Author: Paul Derbyshire (Twizzler) (CC BY-SA 3.0)

Photo 4 - Author: Jerzy Opioła (CC BY-SA 4.0)

Photo 5 - Author: Jerzy Opioła (CC BY-SA 3.0)