About Tapinella atrotomentosa (Batsch) Šutara
The fruit body of Tapinella atrotomentosa is a squat mushroom, with a cap that reaches up to 20 cm (8 in) wide. The cap is sepia or walnut brown, with a rolled rim and a depressed centre. Its gills are cream-yellow and forked. The thick stipe grows out sideways from the mushroom, reaching up to 12 cm long; it is dark brown and covered in dark brown velvety fur. The flesh is yellowish, has been described as appetising in appearance, and is rarely affected by insects, but has an acrid taste. The spore print is yellowish to brownish, and the spores are round to oval, measuring 5–6 μm long.
This saprobic fungus grows on conifer tree stumps. It is distributed across North America, Europe, and Central America (where it occurs in Costa Rica), and extends east into Asia, with records from Pakistan and China. Fruit bodies appear in summer and autumn, and can still grow during drier periods when other mushrooms do not appear.
Tapinella atrotomentosa is generally not considered edible, though it has been used as food in parts of eastern Europe. This species contains toxins that may cause gastrointestinal upset, and poisoning cases have been recorded in European literature. Linus Zeitlmayr reports that young mushrooms are edible, but warns that older mushrooms have a foul bitter or inky flavour and may be poisonous. Boiling the mushrooms and discarding the water is said to reduce the bitter flavour, but the mushrooms remain indigestible for many people. Tests on the chemical composition and free amino acid levels of this mushroom show that it is not notably different from other edible gilled mushrooms such as Armillaria mellea.
