Pileus (Cap): The cap is (1)3%u20137(10) cm broad. Convex to obtusely campanulate with an incurved margin at first, rarely becoming plane, and often are umbonate or with a slight depression in the center. It is viscid when moist from a separable gelatinous pellicle. The margin is slightly translucent-striate when moist. The cap is hygrophanous, yellowish brown to reddish brown with a silvery-blue metallic luster, paler at the margin, and drying to a beige or straw yellow. It readily bruises blue when handled, the younger specimens bruising bluish olivacous or even blackish. The cap often has a great variation in color and form.
Lamellae (Gills): The gills are adnate to sinuate and close to subclose. They are whitish, yellowish grey when young, becoming dark violaceous brown to sepia brown with age; the edges remain slightly whitish.
Stipe (Stem): The stipe is (2)5%u20139(13) cm long and (5)8%u201310(12) mm thick. It is equal or enlarging slightly at the base, and is somewhat flexous, hollow, and subpruinose to floccose. The stipe is whitish to reddish brown or blackish and readily bruises blue. Rhizomorphs are sometimes attached to the base. The veil is well-developed but does not form a permanent annulus.
Microscopic features: The spores are subrhomboid to subellipsoid and (6)6.7%u20138(8.5) x 4%u20136 um. The basidia each produce four spores, and occasionally only two spores. The cheilocystidia are 15%u201322(25) x 4.5%u20136 um and fusoid, with a flexuous neck that is 1%u20132.5 um broad. Psilocybe caerulescens var. caerulescens lacks pleurocystidia.
Season: June through September.
Habitat and Distribution: Psilocybe caerulescens (weilii) grows gregariously to cespitosely, from May to December. Psilocybe weilii is found under Loblolly Pine and Sweet Gum or in bermuda grass or fescue, often in red clay soil that is enriched with pine needles. It also grows in urban lawns and in the deep woods on areas where decaying wood collects. Psilocybe weilii is found only in northern Georgia. Disturbed or cultivated grounds often devoid of herbaceous plants. It often grows in sunny locations, preferring muddy orangish brown soils. Psilocybe caerulescens var. caerulescens was first reported from near Montgomery, Alabama, by Murrill in 1923 on sugarcane mulch, not re-documented from that locality since. It was recently found in South Carolina in September 2008. Psilocybe caerulescens is common and widespread throughout central regions of Mexico, also found in Venezuela and Brazil.