How to identify Butyriboletus frostii

To correctly identify Butyriboletus frostii (Butyriboletus frostii), 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 bright red, but can sometimes be more orange or yellowish-red. It is convex when young, becoming more flattened with age. The surface is dry and can be slightly sticky when wet.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   N/A (pores instead of gills). The pore surface is bright yellow, bruising blue when touched. The pores are small and angular.

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is typically red, often with a yellow base. It is solid and can be slightly reticulated (net-like pattern) near the top.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is yellow, sometimes staining blue when cut or bruised, especially in the cap. This bluing reaction can vary in intensity.

5. 5

   Fruiting body

   Overall growth pattern.

   Medium to large in size, with a striking red cap and stem, and yellow pores.

6. 6

   Habitat

   Where it grows and on what substrate.

   Found in hardwood forests, particularly with oak trees, during summer and fall.

Key Facts

Cap surfaces

dry, slightly sticky when wet

Growth Form

solitary to scattered

Spore Print

olive-brown

Body color

red and yellow

Odor

not distinct

Flesh bruises

sometimes blue

Height

5-15 cm

Cap Diameter

5-15 cm

Fruit body characteristics

• Gill attachment: N/A (pores instead of gills)
• Stem shape: equal to club-shaped
• Stem surface: dry, often with reticulation
• Ring: absent
• Stem cross-section: solid

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