How to identify Périgord Black Truffle

To correctly identify Périgord Black Truffle (Tuber melanosporum), check each of these features in order. Misidentification is the most common cause of mushroom poisoning, so cross-reference multiple sources.

Step-by-step identification

1. 1

   Cap

   Shape, color, surface texture, and diameter.

   Not applicable as it is a subterranean fungus without a cap.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   Not applicable, as truffles are ascomycetes and do not produce gills.

3. 3

   Stem

   Length, shape, surface, and any ring.

   Not applicable, as truffles are subterranean and do not possess a stem.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The gleba (interior flesh) is initially whitish and gradually darkens to very dark brown or purplish-black at maturity, contrasting sharply with the fine, maze-like, non-anastomosing white to off-white sterile veins that traverse it. These veins do not change color upon exposure to air. The texture is firm and dense.

5. 5

   Fruiting body

   Overall growth pattern.

   Globose to irregular in shape, typically 2-10 cm in diameter, though larger specimens can occur. The peridium (outer skin) is firm, rough, and covered in small, pyramidal warts, 2-5 mm wide, often with a slight depression at the apex of each wart. Initially reddish-brown, it matures to a deep charcoal black or purplish-black. The interior (gleba) is solid, firm, and when mature, dark purplish-brown to black, marbled with fine, intricate white or pale, anastomosing veins that do not change color when exposed to air. Spores are brown, ellipsoid to globose, 20-45 x 17-30 µm, reticulate-spiny.

6. 6

   Habitat

   Where it grows and on what substrate.

   Tuber melanosporum is an ectomycorrhizal fungus, forming symbiotic relationships predominantly with oak trees (Quercus species, especially Q. robur, Q. ilex, Q. pubescens), but also with hazel (Corylus avellana), beech (Fagus sylvatica), and linden (Tilia spp.). It prefers calcareous (limestone-rich) soils, well-drained, with a pH between 7.5 and 8.5. It typically grows in relatively shallow soil, often in association with the 'brûlé' phenomenon where vegetation under the host tree is suppressed.

Key Facts

Cap surfaces

Absent (peridium is black, warty with pyramidal warts)

Growth Form

Solitary or in small clusters underground

Spore Print

Brown (the color of the mature gleba due to spores)

Body color

Dark purplish-black to charcoal black (peridium); dark purplish-brown to black with white veins (gleba)

Odor

Strongly aromatic, earthy, musky, complex

Flesh bruises

Veins remain white; gleba maintains its dark color without bruising.

Height

Not applicable (subterranean)

Cap Diameter

2-10 cm (diameter of the fruiting body)

Fruit body characteristics

• Gill attachment: Not applicable
• Stem shape: Not applicable
• Stem surface: Not applicable
• Ring: Not applicable
• Stem cross-section: Not applicable

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