Lactarius pseudomucidus is a fungus native to the northwestern part of North America. It has a charcoal brown cap, smooth and slimy, about 4–10 cm across, initially flat convex, becoming shallowly depressed. Gills are decurrent, with a bluish-gay tinge. Stipe is 40–100 mm tall, hollow, brittle. Flesh gray. Latex is milky white. There is only a slight odor, and the taste slowly becomes acrid. Spores are white in mass, ellipsoid, amyloid, about 8 μm long, with a reticulate decoration on the surface.