How to identify Red-mouthed bolete

To correctly identify Red-mouthed bolete (Boletus erythropus), 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 hemispherical to convex, flattening with age, measuring 5 to 20 cm (2 to 8 inches) in diameter. The color is typically dark brown, reddish-brown, or olivaceous-brown, with a finely velvety or suede-like surface texture, especially when young, becoming smoother with age. It does not crack or fissure extensively. The margin is often inrolled when young.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   Instead of gills, this mushroom has a pore surface. The pores are small, circular, and initially vivid red or crimson, fading somewhat to orange-red with age. They bruise instantly and intensely dark blue or blackish-blue upon touch. The tubes are concolorous with the pores. The pore layer is depressed around the stem.

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is robust and solid, measuring 5 to 15 cm (2 to 6 inches) in height and 1.5 to 5 cm (0.6 to 2 inches) in thickness. It is typically cylindrical to club-shaped, often broader towards the base. The color is yellowish to orange-red or reddish-brown, densely covered with minute red to orange-red, granular or punctate (dotted) points or scales (scabrosities) against a yellow background. This gives it a 'red-dotted' appearance. It lacks a true reticulation (net-like pattern). The base of the stem often displays reddish or brownish stains. The extreme base may show a touch of crimson.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is pale yellow to lemon-yellow. When cut or bruised, it rapidly stains dark blue to indigo, particularly in the cap and upper part of the stem. This bluing reaction is a key identifying feature.

5. 5

   Fruiting body

   Overall growth pattern.

   The fruiting body is stout and fleshy, typical of many boletes, with a distinct cap, pore surface, and stem.

6. 6

   Habitat

   Where it grows and on what substrate.

   Typically found growing solitary or scattered in mixed deciduous and coniferous forests. It forms ectomycorrhizal associations with a wide range of trees, including oaks, beeches, birches, pines, and spruces. It prefers well-drained, acidic to neutral soils.

Key Facts

Cap surfaces

Velvety, suede-like, smooth with age

Growth Form

Solitary or scattered

Spore Print

Olive-brown

Body color

Dark brown cap, red pores, yellow flesh, reddish-dotted stem

Odor

Mild

Flesh bruises

Rapidly and intensely dark blue

Height

5-15 cm (2-6 inches)

Cap Diameter

5-20 cm (2-8 inches)

Fruit body characteristics

• Gill attachment: No gills, pore surface is adnate to depressed around the stem
• Stem shape: Cylindrical to club-shaped, often thicker towards the base
• Stem surface: Yellowish to orange-red, densely covered with minute red to orange-red punctations (dots)
• Ring: Absent
• Stem cross-section: Solid

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