Irpex lacteus

Irpex lacteus (Fr.) Fr.

[Polyporus tulipiferae]

milk-white toothed polypore.
Emberger (2008): Epithet = milky. Genus = a large rake with iron teeth.
Effused polypore with milk-white toothy pores. Pores are lacerate (torn) and turn pale tan in age. Typically has reflexed portions (narrow caps) that fuse into long rows along the edges. Upper side whitish (to pale gray), velvety to whitish, can be ridged (sulcate). Microscopic characters include conspicuous cystidia that are encrusted (like a rock candy stick).
Similar species
Trichaptum is generally more pileate and less effused, and pores turn from violet to cream (not white). Xylodon (was = Schizopora) has generally shallower maze-like pores and no reflexed edges. Trametopsis cervina has reflexed caps that resemble a Trametes and the irregular pores are not deeply lacerate and split. Spongipellis pachyodon has larger caps and is less effused. Some Antrodia may get jagged pores but pores are usually not deeply lacerate and split. Steccherinum and other hydnoid species have rounded teeth or spines rather than flat jagged and split pores.
White rot of hardwoods (angiosperms), rarely on conifers (gymnosperms). Grows often on branches but also on logs or trunks. Occurs on urban Chicago streets on dead branches of honey locust.
Persists year-round.
Cosmopolitan. Widespread in temperate and tropical regions.
Chicago Region status
Very Common. Moffatt (1909) states: Our most common species. It is indeed common here but ranks 5th or more after such species as Stereum complicatum, Trametes versicolor, Trichaptum biforme, Neofavolus alveolaris, and Fuscoporia gilva.
Specimens examined
Found many times around Chicago and on American forays.

Taxon Details and Links

  • Irpex lacteus (Fr.) Fr., Elenchus Fungorum 1: 145 (1828)
  • ≡ Basionym: Sistotrema lacteum Fr., Observationes mycologicae 2: 266 (1818)
  • ≡ Sanctioned: Hydnum lacteum (Fr.) Fr., Systema Mycologicum 1: 412 (1821)
  • = Boletus tulipiferae Schwein., Schriften der Naturforschenden Gesellschaft zu Leipzig 1: 99 (1822)
  • = Polyporus tulipiferae (Schwein.) Overh., [as 'tulipiferus'], Wash. Univ. Stud. 1: 29 (1915)
This species has a long list of synonyms that have been placed in a dozen different genera.
Michael Kuo
Gary Emberger
Photos at Wood Decay Fungi of Living Trees.
Moffatt, W. S. 1909. The Higher Fungi of the Chicago Region: Part I, The Hymenomycetes. Natural History Survey, Bulletin No. VII, Part I. Chicago Academy of Sciences. 156 pp., 24 plates. 10.5962/bhl.title.3605 [Read Part 1 online at Biodiversity Library; Part 2 not found]
Mushroom Observer
Index Fungorum and Species Fungorum

Compare Index Fungorum and Mycobank.

Cite this page as: Leacock, P.R. (2018 Jun 28). Irpex lacteus - MycoGuide. Retrieved from

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