Phellodon melaleucus

Description
Mushroom Identification
Look-Alikes
History
Synonyms

Description

Phellodon melaleucus is a tough inedible fungus. These mycorrhizal species associated primarily with broadleaf trees. It is one of the ‘tooth’ fungi so called as they produce spores on spines on the underside of the cap instead of gills. The cap has a wide white to pale margin contrasting with a concentrically zoned red-brown to black-brown center. It can look as if there is a single fruiting body from above, but several fruiting bodies can fuse together as seen by multiple stems that are often black. If sliced, the flesh is gray-brown, darkening near the stem base. It can smell very strongly of fenugreek (curry powder), especially when dry.

This species occurs in various parts of Europe and has been recorded in North America. It is uncommon in the United Kingdom and very rare in Ireland.

Common names: Gray Tooth.

Mushroom Identification

Cap

Flat-topped or occasionally with a shallow depression, the faintly radially-zoned upper surface is initially velvety and eventually develops radial wrinkles. The cap surface is gray-brown with a much paler marginal region. Usually ranging from 2 to 6cm across, larger specimens tend to have lobed and wavy margins. The fibrous flesh is zoned in shades of brown to reddish-brown; it turns green with KOH.
Spines

The lower (fertile) surface of this hydnoid fungus is covered in white spines that gradually turn brown with age. Spines are up to 3mm long and decurrent to the stem.
Stem

1 - 1.5cm long and 1 - 0 5mm in diameter, the stem is more or less cylindrical, blackish brown, and smooth to finely fibrillose; several stems are sometimes fused at the base.
Spores

Ellipsoidal to subglobose, spiny, 3.5-4.5 x 3-4μm (excluding spines, which are up to 0.5um tall), hyaline, inamyloid.
Spore Print

White.
Odor and Taste

Odor is slightly spicy when old; tastes mild or slightly bitter.
Habitat

Mycorrhizal, in coniferous and broadleaf woodlands, very often under oaks, Beech, and Sweet Chestnut in southern England but also found with pine (especially in central and southern mainland Europe), spruce, and Douglas Fir; usually on acidic sandy soils. Also recorded on acidic heathland with Bilberry.
Season

August to November.

Look-Alikes

The corky tough flesh distinguishes it from tooth fungi in the genera Hydnum, Sarcodon, or Bankera and the white to pale gray-brown spines and white spore print from Hydnellum. The brown cap colors of P. confluens and P. tomentosus distinguish these from P. melaleucus. P.niger is however a very close species. Both have black cap colors and strong fenugreek (curry powder) smell. However, P.niger, as its name suggests, is even blacker, and if it is sliced, the flesh is two-toned with grey on the outside and black in the center. Additionally, the cells of P. melaleucus are olive green to black if mounted in potassium hydroxide compared to the greening cells of P. niger.

Old species of tooth fungi are notoriously difficult to identify and it is not worth trying to do so.

History

In 1815 the great Swedish mycologist Elias Magnus Fries described this species, sanctioning work by Swedish botanist Olof Peter Swartz (1760 - 1818). Fries gave Grey Tooth the scientific name Hydnum melaleucum. In 1879 Finnish mycologist Petter Adolf Karsten (1834 - 1917) transferred the Grey Tooth fungus to the genus Phellodon, renaming it as Phellodon melaleucus.

The genus Phellodon was circumscribed by Finnish mycologist Petter Karsten; the generic name comes from phell- meaning cork, and -don meaning tooth. The specific epithet melaleucus means black and white.