Pseudoinonotus dryadeus

Pseudoinonotus dryadeus (Pers. : Fr.) T. Wagner & M. Fisch.

[previously Inonotus]

oak bracket, warted oak bracket.
Epithet = pertaining to dryad, a wood nymph associated with oak. Genus = false-Inonotus (resembling fiber).
Annual pored bracket without stem. Pores small. At base of a living or dead tree. Starts out as a big lump. Surface exudes a profusion of water droplets when actively growing, leaving dimples in the surface. Forms one or two tiers of shelves. KOH on surface turns blackish (family character). Decayed fruitbodies can be black and fragmented.
Similar species
Compare to other members of the family, such as Inonotus. Those in the Phellinus group tend to be either perennial or smaller. Ischnoderma resinosum exudes droplets but brackets are less robust, more fleshy, and usually on dead wood. Hydnellum are smaller and have teeth underneath.
Parasite on oak trees. Reported on elm and maple; on fir in the west. Causes a white rot of the roots and butt of tree. If you find this fruiting at the base of an urban tree, it is a bad sign of severe rot. It causes branch die off and may weaken base of tree.
In Chicago it starts fruting in August and reaches full size in early September.
Widespread and common in the east. Widespread but less commonly collected in the west.
Chicago Region status
Uncommon. Usually urban areas and on trees near parking lots. One of many reasons not to damage tree bases with lawn mowers or other equipment. The only historic record I could find is from Evanston 1927.
Specimens examined
Nine collections plus 15 observations for Chicago Region.

Taxon Details and Links

  • Pseudoinonotus dryadeus (Pers. : Fr.) T. Wagner & M. Fisch., Mycological Research 105 (7): 781 (2001)
  • ≡ Basionym: Boletus dryadeus Pers., Observationes mycologicae 2: 3 (1799)
  • ≡ Sanctioned: Polyporus dryadeus (Pers.) Fr., Systema Mycologicum 1: 374 (1821)
  • Phellinus dryadeus (Pers. : Fr.) Pat., Essai taxonomique sur les familles et les genres des Hyménomycètes: 97 (1900)
  • Inonotus dryadeus (Pers. : Fr.) Murrill, North American Flora 9 (2): 86 (1908)
Europe, on old Quercus tree.
This species has also been combined into the genera Ischnoderma (1879), Placodes (1886), Fomes (1890), Ungularia (1916), Xanthochrous (1966), and Fomitiporia (1999).
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Cite this page as: Leacock, P.R. (2018 May 07). Pseudoinonotus dryadeus - MycoGuide. Retrieved from

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