How to identify Alder Roll-rim

To correctly identify Alder Roll-rim (Tapinella atrotomentosa), 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 is typically 5-15 cm in diameter, convex to flattened, and dark brown to blackish-brown. The surface is dry and may be slightly velvety. The margin is often inrolled, especially when young.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   The gills are decurrent (running down the stem), close, and yellowish-brown, bruising darker when handled.

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is stout, short, and velvety, with a dark brown to blackish-brown color. It is typically eccentric or lateral, meaning it is attached to the cap off-center.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is thick, firm, and yellowish-brown to brown. It may have a slightly acidic or woody odor.

5. 5

   Fruiting body

   Overall growth pattern.

   The fruiting body of Tapinella atrotomentosa is a mushroom with a cap and stem structure.

6. 6

   Habitat

   Where it grows and on what substrate.

   Tapinella atrotomentosa is commonly found on decaying alder wood, both logs and stumps. It can also be found on other hardwoods and occasionally on conifers.

Key Facts

Cap surfaces

Dry, slightly velvety

Growth Form

Saprophytic

Spore Print

Brown

Body color

Dark brown to blackish-brown

Odor

Slightly acidic or woody

Flesh bruises

Darker

Height

2-8 cm

Cap Diameter

5-15 cm

Fruit body characteristics

• Gill attachment: Decurrent
• Stem shape: Cylindrical, eccentric or lateral
• Stem surface: Velvety
• Ring: Absent
• Stem cross-section: Solid

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