Phlegmacium ponderosum

It was described in 1939 by the American mycologist Alexander H. Smith who classified it as Cortinarius ponderosus.[2]

In 2022 the species was transferred from Cortinarius and reclassified as Phlegmacium ponderosum based on genomic data.[3]

This mushroom is one of the largest mushrooms in the family Cortinariaceae, with a convex cap that ranges from 10–30 cm (4–12 in)[4] and becomes plane in age. It often has an olive metallic tinge, and the surface is viscid, often with small rusty brown scales.[4] The margin is ocher and remains inrolled until the mushroom is fully mature. The flesh of the mushroom is yellow-white, thick and firm, with a mild to sour odor.[4] The gills are rusty brown, adnate[4] and slightly decurrent. The stalk is 8–20 cm (3–8 in) thick, 4–10 cm wide, and bulbous at the base.[4] It has a slimy yellow universal veil, and the cortina leaves a rusty brown hairy area on the upper stalk. The spores are brown and elliptical.[4]

Its edibility is unknown, but it is not recommended due to its similarity to deadly poisonous species.[4]

Cortinarius infractus is a similar species that usually has a smaller cap.[4]

The specific epithet ponderosum (originally ponderosus) is named for the Pinus ponderosa trees which Smith observed the mushrooms growing under.[2]

Smith observed the mushrooms growing under Pinus ponderosa and Quercus (Oak) species near Cave City in Oregon and under Spruce trees near Crescent City, California.[2]

Spores 1000x

• List of Cortinarius species

• -- Cortinarius ponderosus
• Cortinarius ponderosus photo
• Cortinarius ponderosus info