Hapalopilus rutilans

Hapalopilus rutilans is a species of polypore fungus in the family Polyporaceae. Officially described in 1821, it was transferred to its current genus Hapalopilus six decades later. It is commonly known as the tender nesting polypore, purple dye polypore, or the cinnamon bracket. The species grows on the fallen or standing dead wood of deciduous trees, in which it fruits singly, in groups, fused, or in overlapping clusters. Fruit bodies are in the form of kidney-shaped to semicircular, cinnamon-orange-brown brackets. The underside of the fruit body features a yellowish to brownish pore surface with tiny angular pores, from which spores are released. When an alkaline solution is placed on the fungus, the flesh turns violet. The widely distributed species is found on five continents. The fruit bodies are neurotoxic if ingested, an effect attributable to the compound polyporic acid, which is present in high concentrations. The fungus is used in mushroom dyeing to produce purple colors.