How to identify Black Earth Tongue

To correctly identify Black Earth Tongue (Geoglossum umbratile), 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.

   The 'cap' or fertile head is typically 1-3 cm tall and 0.5-1.5 cm wide, club-shaped, spatulate, or somewhat compressed. It is black, smooth to minutely velvety, and often slightly viscid when moist. The margin is usually entire.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   Geoglossum umbratile, like all earth tongues, is an ascomycete and does not possess gills. The spores are produced on the surface of the club-shaped head (hymenium).

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is continuous with the head, typically 1-5 cm long and 0.2-0.8 cm thick. It is black, smooth to minutely velvety, and often slightly viscid when moist, similar in texture and color to the head. It can be cylindrical or slightly compressed.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is thin, tough, and blackish, with no distinctive odor or taste.

5. 5

   Fruiting body

   Overall growth pattern.

   The fruiting body is club-shaped to spatulate, often somewhat flattened or compressed, and typically measures 2-8 cm in height. It is entirely black or very dark brown, with a smooth to slightly velvety surface. The upper, fertile portion (head) is usually distinct from the stem, though sometimes gradually tapering.

6. 6

   Habitat

   Where it grows and on what substrate.

   Saprobic, growing solitarily or in scattered groups on soil, often among mosses, in grasslands, open woodlands, and disturbed areas. It prefers moist, humus-rich soils.

Key Facts

Cap surfaces

Smooth to minutely velvety, often slightly viscid when moist

Growth Form

Solitary or scattered

Spore Print

Dark brown to black (spores are dark)

Body color

Black to very dark brown

Odor

Indistinct

Flesh bruises

Does not bruise

Height

2-8 cm

Cap Diameter

0.5-1.5 cm (width of the head)

Fruit body characteristics

• Gill attachment: Not applicable (ascomycete, no gills)
• Stem shape: Cylindrical to compressed
• Stem surface: Smooth to minutely velvety, often slightly viscid when moist
• Ring: Absent
• Stem cross-section: Solid

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