Tuberous Polypore

not listed

not listed

not listed

Tuberous Polypore is an uncommon bracket fungus. From a distance it can be mistaken for a gilled mushroom. It occurs in Europe, western Asia, Japan, and the Americas. It occurs across the United States where it is most abundant but not common west of the Rocky Mountains, and is widely scattered and uncommon elsewhere. It is uncommon in Minnesota. It is found in the spring and fall in deciduous and mixed woodlands. It grows on the ground, on wood, and on wood buried in the ground. When on the ground it often appears in groups of two or three. When on wood it usually appears alone.

When it first appears, the cap is convex when viewed from the side and round, not bracket-shaped, when viewed from above. The upper surface is dry and tan to brown or yellowish-brown. The margins are curved under. As it ages it becomes flat with a depressed center or with a raised bump in the center (umbonate). The mature cap is 1½″ to 6″ (4 to 15 cm) in diameter, 3⁄16″ to ⅜″ (5 to 10 mm) thick, funnel-shaped, and darker, sometimes dark orangish-brown. The upper surface is covered with dark fibers (fibrils) and scales. The scales often have erect tips. The margins are sometimes curved upward and are often indented or lobed.

The stalk is solid, tough, 1″ to 4″ (2.5 to 10 cm) long, and ⅜″ to 1″ (1 to 2.5 cm) thick, sometimes thicker. It may be attached centrally, off-centered, or sometimes at one side.

When growing on the ground it is attached to a large underground sclerotium-like tuber. When on wood it sometimes has a connection through the wood to an underground tuber. A sclerotium is a hard mass of mycelium that contains food reserves and can remain dormant for long periods. The sclerotium of one mushroom was used by American Indians as a food source. The sclerotium-like tuber of Tuberous Polypore also stores food reserves, but it contains sand and dirt and is not edible. It is dark brown to black and is irregularly shaped.

The pore surface is white to pale tan. There are 1 to 3 pores per millimeter. The tubes are 1⁄32″to ⅛″ (1 to 3 mm) long. The pore surface usually runs down the stalk.

The flesh is pale and thin. It is edible when young and fresh after being thoroughly cooked. On older specimens the flesh is hard, tough, and inedible.

The spore print is white.

Spring and fall

Sources

4, 24, 26, 29, 30, 77.

Uncommon in Minnesota

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Location: Hennepin County