Rigidoporus ulmarius identification

About mushroom

Rigidoporus ulmarius is a plant pathogen found mainly on broad-leaved trees. White/cream coloured thick woody bracket, often covered in algae giving it a green look. Lower rim edge can show cinamon colour, which is the tube layer. Pores white at first then developing orange/red, fading to pink.

Trees list: Elm, Horse Chestnut, Poplar, Oak, Maple.
Mode Of Decay: Parasitic. Brown Rot leading to cubical cracks toward the core of the trunk.

Bracket 12-50cm across ( rarely above 50 ), 6-15cm wide, 4-8cm thick, bracket-shaped, hard and woody, surface knobbly; concentrically ridged, white to ochraceous becoming dirty-brown in older specimens.

Tubes 1-5mm long in each layer, pinkish to orange when young, browning with age, each layer separated by a thin contrasting band of white flesh. Pores 5-8 per mm, red-orange fading to clay-pink or buff with age.
Spores pale yellow, globose, 6-7.5um in diameter.

Hyphal structure monomitic; generative hyphae lacking clamps. Habitat at the base of trunks of deciduous trees, usually elm. Season all year, perennial. Common. Not edible. Found In Europe.


Rigidoporus ulmarius is a member of Shelf Fungi

Shelf Fungi (Order Polyporales)

The Polyporales are an order of fungi in the division Basidiomycota, subclass Agaricomycetidae. The order includes some (but not all) polypores as well as many corticioid fungi and a few agarics (mainly in the genus Lentinus). Species within the order are saprotrophic, most of them wood-rotters. Those of economic importance include several important pathogens of forest and amenity trees and a few species that cause damage by rotting structural timber. Some of the Polyporales are commercially cultivated and marketed for use as food items or in traditional Chinese medicine.


Common bracket found on Willow, Elm and Horse Chestnut.
Sometimes mistaken for 'Perenniporia fraxinea' which favours Poplar, Elm and Ash.
Both have perenial brackets.

Although niether are on the Red data list of threatened brittish fungi,
P. fraxinea is thought to be somewhat rare.

The easy way to distinguish the difference, is when you cut a slice out.
P. fraxinea has flesh and tube layers of the same colour. Whereas Rigi has orange fading tubes which contrast sharply against the spongy white flesh.

Green algal and/or moss growth on the top surface is pretty typical.
Decay type is Brown cubicle rot.



The largest known basidioma (mushroom or fruiting body) was that of a Rigidioporus ulmarius (Agaricomycetes), hidden-away in a shady corner of the Royal Botanic Gardens, Kew, Richmond, Surrey, England. This fruiting body was mentioned in the Guinness Book of World Records (Matthews, 1994). At the beginning of every New Year the Annual Mensuration Ceremony of the fruiting body took place, and on 19 January 1996 it had increased to 170 cm maximum length (up from 159 in 1995) and 146 cm maximum width (up from 140 in 1995). It also grew 4 cm taller from the soil level, measuring 54 cm. The weight of the fruiting body was estimated to be 284 kg (625 pounds)! Amid rumors of its destruction, Dr. Brian M. Spooner, Head of Mycology, Royal Botanic Gardens, has brought us up to date on the fate of the record specimen. Unfortunately, the basidioma began to rot at the edges a few years ago, likely because the hyphal body of the fungus digested away its elm root substrate, reminding us that a fungus needs a good dispersal system to escape the substrate that eventually inevitably is destroyed. In the life of the fruiting body many trillions of spores must have been produced, and some of these surely fell on an appropiate substrate to establish a new infection. The final insult to the fruiting body came from a fox that burrowed under one side and caused it to collapse.


P.S. Often confused with Perenniporia fraxinia


Keywords: wald, autumn, herbst, pilz, baumpilz, hard, elm, hart, oktober, holzig, october, ungenießbar, ungeniessbar, porling, ulmenporling, rigidoporus ulmarius, knobbly, not edible



Rigidoporus ulmarius (Sowerby) Imazeki 1952
Ungulina cytisina (Berk.) Murashk. 1940
Polyporus cytisinus Berk. 1836
Scindalma ulmarium (Sowerby) Kuntze 1898
Rigidoporus geotropus (Cooke) Imazeki 1955
Coriolus actinobolus (Mont.) Pat. 1903
Rigidoporus geotropus (Cooke) Dhanda 1981
Fomes geotropus (Cooke) Cooke 1885
Haploporus cytisinus (Berk.) Domanski 1973
Leucofomes ulmarius (Sowerby) Kotl. & Pouzar 1957
Fomitopsis ulmaria (Sowerby) Bondartsev & Singer 1941
Polyporus ulmarius (Sowerby) Fr. 1821
Ungulina incana (Quél.) Pat. 1900
Polyporus geotropus Cooke 1884
Fomes ulmarius (Sowerby) Gillet 1878
Microporus actinobolus (Mont.) Kuntze 1898
Polyporus fraxineus Lloyd 1915
Scindalma cytisinum (Berk.) Kuntze 1898
Fomes ulmarius Fr. 1874
Boletus ulmarius Sowerby 1797
Mensularia ulmaria (Sowerby) Lázaro Ibiza 1916
Polyporus actinobolus Mont. 1854
Placodes ulmarius (Sowerby) Quél. 1886
Placodes incanus Quél. 1886
Polyporus sublinguaeformis Schulzer 1882
Scindalma geotropum (Cooke) Kuntze 1898
Ungulina ulmaria (Sowerby) Pat. 1900
Polystictus actinobolus (Mont.) Cooke 1886

Rigidoporus ulmarius photos

More info about Rigidoporus ulmarius mushroom

Stem type:
rudimentary or absent
Grows on wood
Spore colour:
cream or yellowish
Fungus colour:
White to cream
Grey to beige
Normal size:
over 15cm
Pore material cannot be seperated from flesh of the cap
Giant elm bracket, Iepebuisjeszwam, Haplopore du frene, Polypore de lorme, Ulmenporling, Parasito facultativo
Last modification: 2015-10-02 06:18:56

Rigidoporus ulmarius comments

2015-10-15 09:39:35

Giant elm bracket, Iepebuisjeszwam, Haplopore du frêne, Polypore de l'orme, Ulmenporling

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