Porphyrellus porphyrosporus: The Ultimate Mushroom Guide
About The Porphyrellus porphyrosporus Mushroom
Porphyrellus porphyrosporus is a rare fungus belonging to the family Boletaceae. With its purple-brown cap and stem, Porphyrellus porphyrosporus is not easy to spot, despite its large size. This summer and autumn species occur under pines, but can also be found beneath deciduous trees. Its most distinctive features are the purple-brown spore print and the blue-green color of the flesh at the top of the stem and above the hymenium.
An unusual aspect of Porphyrellus porphyrosporus is the color changes it exhibits when cut or bruised. These typically are slow to develop and usually involve an initial change from cream to pale pink, then greyish-black, or in some cases, at first pale blue, then greyish-black. This species often stains wax paper collecting bags blue.
This is a widespread species of Europe, especially in the north, but is nowhere particularly common. The fruit bodies appear from late summer to autumn, often in small groups, associated with broad-leaved trees such as beech and oak.
This mushroom is reported to have a sour taste, and it is best treated as inedible if not for that reason then for its rarity.
Other names: Dark Bolete, Dusky Bolete.
Porphyrellus porphyrosporus Identification
This somber mushroom has a dark brown cap with a noticeably paler margin. Initially convex, caps expand and sometimes become irregularly lobed.
6 to 15 cm in diameter when fully expanded, the caps have soft buff flesh with a vinaceous tinge.
Tubes and Pores
The tubes and pores are greyish-yellow at first (as in the youngish specimen shown here) but, as the fruiting body begins releasing spores, the pores turn brown. When cut or bruised, the tubes turn blue-green.
1 to 3cm in diameter and 5 to 12cm tall, the stems of this species are tobacco brown and slightly velvety to the touch when young, becoming smooth as the fruiting body matures.
The stem flesh is buff, turning slightly blue-green near the apex when cut.
Ellipsoidal to subfusiform; smooth, thick-walled; 14-17.0 x 6.0-7.5 µm.
Odor and Taste
Unpleasant sour taste and odor.
The Bay Bolete, Imleria badia, is similar but with a shiny cap when fully developed; its tubes turn blue when bruised.
Porphyrellus porphyrosporus Taxonomy & Etymology
First described by Elias Magnus Fries and Fredrik Christopher Theodor Hök (1807 - 1877) in their thesis Boleti, Fungorum generis, illustratio in 1835, where it appeared under the scientific name Boletus porphyrosporus, the Dusky Bolete was transferred to the genus Porphyrellus 110 years later by the French mycologist Jean-Edouard Gilbert (1888 - 1954), and this was its generally-accepted scientific name until quite recently. The currently-accepted name Tylopilus porphyrosporus dates from a 1971 publication by American mycologists Alexander Hanchett Smith (1904 - 1986) and Harry Delbert Thiers (1919 - 2000).
Among the many synonyms of Tylopilus porphyrosporus (Fr. & Hök) A.H. Sm. & Thiers are Porphyrellus porphyrosporus (Fr. & Hök) E.-J. Gilbert, Krombholziella pseudoscaber (Secr. ex Singer), Boletus porphyrosporus Fr. & Hök, Phaeoporus porphyrosporus (Fr. & Hök) J. Bataille, and Porphyrellus pseudoscaber Secr. ex Singer.
The Dusky Bolete gets its common name and its specific epithet from its dark purplish-brown colors.
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