prl11610 prl12292

Irpex lacteus (Fr.) Fr.

Elenchus Fungorum 1: 145 (1828)

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 in Chicago 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.
This species has a long list of synonyms that have been placed in a dozen different genera.
Specimens examined:
Found many times around Chicago and on American forays.
Description links:
Michael Kuo, MushroomExpert.Com.
Gary Emberger, Messiah College.
Related links:
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.
Photos at Wood Decay Fungi of Living Trees.
Records online:
Mushroom Observer ; MycoPortal
Taxon links:
177211 MycoBank ; Index Fungorum ; Species Fungorum