About Armillaria sinapina Bérubé & Dessur.
This fungus has a brownish cap that measures 2–8 centimetres (3⁄4–3+1⁄4 inches) wide. Its stem is white, fibrous, and can grow up to 10 centimetres (4 inches) long. Both the flesh and spore print of Armillaria sinapina are whitish, and its mycelium is bioluminescent. Armillaria sinapina is a plant pathogenic fungus that causes Armillaria root disease. It has been found growing on a variety of tree host species in Alaska.