What You Should Know
Stereum rugosum is distinguished from most other crusts that occur on hardwoods by the characteristic of bleeding and remaining red when it has been scratched. It is a very common but often overlooked crust fungus.
This fungus is abundant and widespread throughout Britain and Ireland. On mainland Europe, this wood-rotting crust fungus is found from Scandinavia right down to the Mediterranean region, and its range extends eastwards into Asia's temperate regions too. In North America, this crust fungus is also very common.
Other names: Bleeding Broadleaf Crust.
Stereum rugosum Mushroom Identification
Spread out or spread out with a bent edge, 0.5 – 5 mm thick, rarely in the form of small bent, tile-like caps, leathery, corky, brown, initially hairy, later rough, smooth, with a thickened wavy white sterile edge.
The hymenophore is smooth or tuberous, gray, light brown, reddish-brown, covered with a grayish coating, reddens in places of contact, and cracks when drying.
The flesh is hard, leathery, crusty, light ocher or grayish ocher, without a pronounced smell, on the fracture and in the places of contact it emits a red milky juice.
7-12 * 3-7 μm, cylindrical or elliptic-cylindrical in shape, flattened on one side, with rounded edges, with a smooth surface, colorless.
It grows from the beginning of spring until the very frosts, on stumps, on fallen branches, on fallen trunks, on live weakened trunks of deciduous trees, mainly on oaks, birches, aspens, alders, willows, hazel.
Stereum rugosum Look-Alikes
Is darker and grows mainly on dead trunks and branches of oak trees, Quercus sp.; its spores are somewhat smaller than those of Stereum rugosum.
Has an upper surface that is zoned in various shades of grayish-orange or grayish white; it usually forms reflexed crusts or brackets.
Is hairy on its upper surface and often forms reflexed crusts or brackets.
Stereum rugosum Taxonomy and Etymology
This crust fungus was described in 1801 by Christiaan Hendrik Persoon, who gave it the scientific name Thelephora rugosa.
In 1838 Swedish mycologist Elias Magnus Fries transferred this species to the genus Stereum, and its scientific name, still generally accepted today, became Stereum rugosum.
Stereum, the generic name, means tough, and crust fungi in this genus certainly can be difficult to tear when you want to take a small sample for investigation. The specific epithet rugosum refers to the fact that the fertile surface of this crust fungus becomes red (rugose) when scratched.
Stereum rugosum Synonyms
Thelephora rugosa (Pers.) Pers., 1801
Gymnoderma rugosum (Pers.) Hoffm., 1811
Haematostereum rugosum (Pers.) Pouzar, 1959
Corticium boltonii Fr., 1838
Corticium triviale Speg., 1888
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