How to identify Bay Polypore

To correctly identify Bay Polypore (Polyporus durus), 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 measures 5-20 cm (2-8 inches) in diameter, and is convex to depressed in the center, often irregular to wavy. The color ranges from dull brown to a rich bay-brown or reddish-brown, often paler towards the margin and sometimes with darker concentric zones. The surface is smooth, dry, and often becomes finely radially wrinkled with age. It can be somewhat shiny when fresh.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   Instead of gills, Polyporus durus has a poroid hymenophore on the underside of the cap. The pores are small, 3-5 per millimeter, circular to angular, and whitish to cream-colored when young, aging to yellowish or brownish. The pore surface is often decurrent down the stem.

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem (stipe) is central to eccentric, occasionally lateral, and measures 3-10 cm (1.2-4 inches) in length and 1-3 cm (0.4-1.2 inches) in thickness. It is typically tough to woody, cylindrical or slightly tapering towards the base, and often darker brown to blackish, especially at the base where it connects to the buried wood. The surface is often finely velvety or pruinose, becoming smoother with age. It can be deeply rooted in the substrate.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is tough, leathery, and whitish to pale cream-colored, typically 0.5-2 cm thick. It does not change color when cut or bruised. It has a mild, indistinct odor and taste.

5. 5

   Fruiting body

   Overall growth pattern.

   The fruiting body is a centrally to eccentrically stipitate polypore, meaning it has a stem. It typically grows individually or in small clusters. When young, it can be somewhat fleshy, becoming tough and leathery to woody with age. It is poroid.

6. 6

   Habitat

   Where it grows and on what substrate.

   Typically found on dead hardwood, often emerging from buried wood or roots, giving the appearance of growing terrestrially. Less commonly on conifer wood. It acts as a saprobe, decomposing lignin and cellulose.

Key Facts

Cap surfaces

Smooth, dry, radially wrinkled with age, sometimes shiny when fresh

Growth Form

Solitary to clustered, growing from buried wood

Spore Print

White

Body color

Cap: Dull brown to bay-brown; Pores: Whitish to cream, aging yellow-brown; Stem: Brown to blackish, especially at base

Odor

Nondescript or mild

Flesh bruises

Does not bruise or change color

Height

Cap diameter 5-20 cm (2-8 inches); Stem length 3-10 cm (1.2-4 inches)

Cap Diameter

5-20 cm (2-8 inches)

Fruit body characteristics

• Gill attachment: Not applicable (poroid)
• Stem shape: Cylindrical to slightly tapering towards base
• Stem surface: Finely velvety or pruinose, becoming smoother
• Ring: Absent
• Stem cross-section: Solid, tough to woody

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