Habitat: Gregarious in swamps and bogs
Spores: August-October
Conservation Status: Not of concern
Cap: 1.5-5 cm across, conic-campanulate or convex; dark reddish brown, becoming blackish brown with age; pale tan when faded, margin striate when moist, smooth, viscid. Gills: adnate, crowded, broad; pale cinnamon buff, then dark violaceous brown when mature. Stem: 60-120 x 2-4 mm, equal, flexuous, fibrous; covered with pale fibrils, becoming darker brown from the base up with age. Flesh thin; pallid. Odor slight, mealy. Taste mealy. Spores: Purple brown, ellipsoid.
Sources: Phillips, Roger. Mushrooms and Other Fungi of North America. Buffalo, Firefly Books Ltd. 2010.
PNW Herbaria: Specimen records of Psilocybe atrobrunnea in the Consortium of Pacific Northwest Herbaria database
CalPhotos: Psilocybe atrobrunnea photos