Inonotus dryadeus identification

About mushroom

Inonotus dryadeus, commonly known as oak bracket, warted oak polypore, weeping polypore or weeping conk, is an inedible species of fungus belonging to the genus Inonotus, which consists of bracket fungi with fibrous flesh. Most often found growing at the base of oak trees, it causes white rot and decay of the trunks. It secretes an amber liquid which weeps from tubes in its upper surface.

Bracket 10x65cm across,
5x25cm wide,
2x12cm thick, or sometimes forming large, irregular cushions, corky;

Upper surface uneven, white-grey becoming brownish, finally very dark, margin broadly rounded and paler, exuding drops of yellowish liquid.

Flesh rusty brown, fibrous. Tubes 5x20mm long, rusty-brown.
Pores 3x4 per mm, circular then angular, white-grey becoming rusty. Spores white to yellowish, subglobose, 7x9x6.5x7.5m.

Hyphal structure monomitic; generative hyphae lacking clamp-connections.

Setae in the tubes dark brown with swollen base and hooked pointed tips. Habitat parasitic on various species of oak, found at the base of trunks. Season all year. Uncommon.


Ecology: Parasitic on living oaks in eastern North America and, in the west, on true firs; causing a white butt rot and root rot; annual; growing alone, gregariously, or in shelving clusters; summer and fall (or over winter in warm climates); fairly widely distributed in North America but apparently absent in the Great Plains and Rocky Mountains.

Cap: Up to 40 cm across; semicircular, kidney-shaped, cushion-shaped, or irregular; usually convex; finely velvety, becoming bald with age; often lumpy; buff to dull yellow, becoming brown with age; often exuding drops of amber liquid when fresh, especially along the margin; the margin thick.

Pore Surface: Buff to yellowish when young, becoming brown; bruising slowly brown; exuding drops of amber liquid when fresh and young; with 4-6 circular to angular pores per mm; tubes to 2 cm deep.

Stem: Absent.

Flesh: Yellowish brown becoming reddish brown; soft, becoming leathery or corky; zoned.

Chemical Reactions: Flesh black with KOH.

Spore Print: Yellowish to brownish.

Microscopic Features: Spores 6-8 x 5-7 µ; smooth; subglobose; hyaline in KOH; dextrinoid. Setae usually present but sometimes very rare; to about 40 x 15 µ; usually curved. Contextual hyphae thin- to thick-walled; simple-septate.


• At ground level attached to the base and larger
roots of living trees
• On stumps or dead trees
Fruiting Time of Year
• Summer through fall
Fruiting (Hymenial) Surface
• Small pores and gray-brown or darker
Type of Decay
• White root and butt rot with most of the decay
concentrated in larger roots
Mode of Action
• Moderately slow progressing root rot eventually
leading to root failure
• Common
Tree Health Symptoms
• Often none other than the appearance of the
fruiting bodies and extensively decayed root
when a tree fails


A basidiomycetes widespread and fairly common in Britain attacking various species of oak (Quercus), in my experience this year it has been seen on a regular basis. The fungus is sometimes also found on horse chestnut, sweet chestnut, beech, London plane, elm and more rarely on conifers. The fruiting body (Sporophore) is not very regular in its appearance, and quite often several years may elapse between the production of the fruiting body on an infected tree. The fruiting body is usually seen only on large, old living trees and occurs almost invariably near the butt.

Fruiting Body
It is a thick lumpy bracket, being sessile (without stalk) and can measure up to 300mm across and 80mm thick. Sometimes the fruiting bodies are imbricated (arranged so as to overlap) in groups. The upper surface colour is at first pale chamois yellow, later becoming brown. A constant and very characteristic feature of this fungus is the presence of drops of coloured liquid in little round depressions on the margin of the actively growing fruit-body. These depressions may persist after the drops have evaporated. The underside bears small whitish pores, and the flesh and tubes are rusty brown. The consistency of the flesh is soft at first, later becoming corky and then brittle with age. The fruiting bodies appear in the early Autumn and decompose during the winter turning black.

Colonisation Strategy
The attack is more or less confined to the heartwood and never spreads very far up the trunk, at most reaching 2 metres above soil level.

Inonotus dryadeus photos

More info about Inonotus dryadeus mushroom

Stem type:
rudimentary or absent
Grows in woods
Grows on wood
Spore colour:
Light to dark brown
Cap type:
Fungus colour:
White to cream
Normal size:
over 15cm
North America
Pore material cannot be seperated from flesh of the cap
k`nnyez` tapl`, K`rges rozsd`stapl`, Eichenporling, oak bracket, warted oak polypore, Weeping Oak Bracket, weeping polypore, weeping conk, Polyporus dryadeus
Last modification: 2015-10-21 12:13:53

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