Psilocybe liniformans var. americana
Cap: 1 — 2.5 cm Convex to nearly plane, sometimes broadly umbonate but not papillate, smooth, dull grayish brown to slightly olivacous, more reddish at the center, hygrophanous, becoming straw brown when dry with the center remaining more brownish. Sometimes with a bluish green tone, or olivacous tones at the margin when young.
Gills: Adnexed, subdistant, broad, dark chocolate brown to purplish brown with age.
Spores: Dark purple brown, ellipsoid, 13 — 14.5 by 7.5 — 8.8(10)µm.
Stipe: 1.4 — 3.0 cm by 1 — 2 mm equal, enlarging at the base. Whitish to very pale brownish, darker below, bruising blue, finely fibrillose in the lower portion. Partial veil is thin and soon disappears.
Taste: Weak to somewhat farinaceous.
Odor: Strongly aromatic to farinaceous.
Microscopic features: Basidia 4-spored, Pleurocystidia absent. Cheilocystidia 22 — 33 by 5.5 — 9 µm, lageniform with an extended neck.
Psilocybe liniformans var. americana, is a psilocybin mushroom of the Agaricales family, in the section Semilanceatae, having psilocybin as its main active compound.
This mushroom is very close to the type variety, the main difference is the lack of a gelatinous layer on the edge of the lamellae and the terricolous habitat.
Summer to early winter, has been collected in Washington, Oregon, and Michigan, has also been reported from Chile where it fruits in the spring.
Scattered to gregarious in rich pastures or grasslands.