Milk-white Toothed Polypore - Species Profile
Conservation • Description • Habitat • Ecology • Distribution • Taxonomy
Conservation Status
IUCN Red List
not listed
NatureServe
not listed
Minnesota
not listed
Description
Milk-white Toothed Polypore is widespread in Europe and North America. It is very common in the eastern United States to the Midwest, including Minnesota, but rare in the Southwest. It grows flat (resupinate) on the bottom and sides of logs and fallen branches of hardwood trees, infrequently also on conifers. It usually obtains its nutrients from dead wood (saprobic), possibly also from live cherry wood (parasitic). It is exceptionally resistant to pollution toxicity.
The fruiting body is a patch of pore surface spread out flat (effused) on a branch or log (substrate). It is dry, stiff, and white, off-white, or cream-colored. Adjacent patches often fuse together creating a long row. There are 2 or 3 pores every thirty-second of an inch (1 mm). The pore walls are thin and disintegrate unevenly. As the walls break down the spore surface becomes maze-like. Eventually, only flattened, tooth-like projections less than ¼″ (6 mm) long remain. When growing on the side of a log or branch it may develop shelf-like caps. If present, the cap is ⅜″ to 1½″ wide, whitish to grayish, often concentrically zoned, and densely covered with velvety hairs. There is no stem. The flesh is thin and tough. It is not edible.
Similar Species
Habitat and Hosts
Deciduous and mixed forests, urban areas.
Dead hardwood logs and branches, infrequently on conifers
Ecology
Season
Annual but persists year-round
Distribution
Sources
Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 2/18/2026).
Irpex lacteus (Fr.) Fr. in GBIF Secretariat (2023). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org. Accessed 2/18/2026.
Mycology Collections Portal (MyCoPortal) https://www.mycoportal.org/portal/collections/index.php). Accessed 2/18/2026.
Occurrence
Very common in Minnesota forests
Taxonomy
Kingdom
Fungi (Fungi)
Subkingdom
Dikarya
Phylum
Basidiomycota (Basidiomycete Fungi)
Subphylum
Agaricomycotina (Higher Basidiomycetes)
Class
Agaricomycetes (Mushrooms, Bracket Fungi, Puffballs, and Allies)
Order
Polyporales (Shelf Fungi)
Family
Irpicaceae
Genus
Irpex
Family
There is some disagreement about the family to which the genus Irpex belongs. MycoBank, MushroomObserver, GBIF, and NCBI place it in Irpicaceae, Fungi Growing on Wood (Gary Emberger, Messiah College) in Phanerochaetaceae, Encyclopedia of Life and MycoPortal in Meruliaceae, and MushroomExpert and Discover Life in Steccherinaceae. Until 2019, Index Fungiforum formerly placed it in Meruliacea, but very recently transferred it to Irpicaceae.
Subordinate Taxa
Synonyms
Boletus cinerascens
Boletus tulipiferae
Coriolus lacteus
Coriolus tulipiferae
Daedalea diabolica
Hirschioporus lacteus
Hydnum lacteum
Irpex bresadolae
Irpex diabolicus
Irpex hirsutus
Irpex lacteus
Irpex pallescens
Irpex sinuosus
Irpiciporus lacteus
Irpiciporus tulipiferae
Microporus chartaceus
Microporus cinerascens
Polyporus chartaceus
Polyporus tulipiferae
Polystictus bresadolae
Polystictus chartaceus
Polystictus cinerascens
Polystictus cinerescens
Polystictus tulipiferae
Poria cincinnati
Poria tulipiferae
Sistotrema lacteum
Steccherinum lacteum
Trametes lactea
Xylodon bresadolae
Xylodon hirsutus
Xylodon lacteus
Xylodon pallescens
Xylodon sinuosus
Common Names
Milk-white Toothed Polypore
Milk-white Toothed Polypore
