Psilocybe weilii is a recently-described species from the State of Georgia in the USA. Locally known before being recognized by science in 1995, this species was frequently mistaken for P. caerulescens var. caerulescens due to their similar appearance. Both share a strong bluing reaction that can leave aged or damaged samples of P. weilii dark blue or even black.
It has preferences for its location, usually restricted to clay-rich soil. P. weilii is commonly found near American Sweetgum (Liquidambar styraciflua) and Loblolly Pine (Pinus taeda); rarely it occurs in Bermuda Grass or Fescue, occasionally in urban lawns or on decaying wood in deep forest. Despite this array, P. weilii is restricted in its natural range to northwestern Georgia.
This species is considered highly potent, with moderate psilocybin, high relative psilocin and trace baeocystin. It is rarely cultivated due to its slow growth and fickle preference for substrate, most accounts of its potency are from wild specimens. Despite where it is found, P. weilii is said to have a cucumber-like scent and flavour, with generally floury undertones.
P. weilii has a few features that are common among the potent Psilocybe. The edge of the cap is variable: curved in when young, rippled or wavy when middle aged, straight and flat when older. It is always somewhat sticky to the touch when it is wet, with a removable jelly-like covering and translucent striations near the edges.
The few characteristics that set P. weilii apart are the commonly found fringes on their cap. White, fibrous or scale-like, traces can be found on the edge. Further, wooly or hairy patches near the base of the stipe can assist in identifying this species.
Though rare and with a highly restricted range, P. weilii is a highly sought-after species with renowned potency. Rarely grown indoors or cultivated commercially, this find is only likely to occur in its small natural range.