Psilocybe weilii

Psilocybe weilii caps range from (2)3 to 6(8.5) cm in diameter and are obtusely conic to convex to campanulate. The margin is incurved or inrolled when young, becoming irregularly lobulated then straight with age. Psilocybe weilii are subumbonate, hygrophanous, glabrous, and subviscid when moist from the separable gelatinous pellicle. It is translucent-striate at the margin, and purple brown or chestnut brown to dark brown, fading to buff or straw yellow as it dries, with the center remaining blackish brown. Psilocybe weilii often have white scale-like remnants along the margin. The mushroom flesh is white, bruising a strong blue, with some specimens becoming completely blue-black.

Gills can be subadnate to sinuate, and are closely aligned. They are cream to light brown or brownish-yellow, becoming purple brown as the spores mature. The edges are hairy, with small tufts (sub floccose) and whitish.

Spores of this mushroom are dark violet brown, subrhomboid to subellipsoid, and are (5.5)6 to 7(7.5) µm by 5 to 6(6.5) µm. They are thick-walled with broad germ pores.

The stipe or stalk is (2.5)4 to 7 cm long and (4)5 to 10 mm thick. It has an equal structure, and is slightly subulbous. It is hollow, and whitish to yellowish becoming bluish black and drying to grayish straw with vinaceous (maroon) tones. Whitish, woolly (subfloccose) patches are located near the base. The stipe is pruinose (powdery) or smooth towards the upper region. The velum sometimes leaves a partial annular (ringed) zone. It bruises bluish to blackish when injured, sometimes with the entire stipe completely blue or with vinaceous tones.