The Psilocybe Semilanceata species is one of the oldest and most commonly recognized Psilocybe mushrooms. The name is derived from the latin “semi-lanceata” meaning “spear-shaped”. It has a conical or bell-shaped cap throughout its life cycle, dissimilar to most other Psilocybe's whose caps broaden with age. It was first cataloged by Elias Magnus Fries as agaricus semilanceatus in his 1838 publication Epicrisis Systematis Mycologici. It was subsequently transferred to Psilocybe in 1871 when many sub-groupings of agaricus were raised to the level of genus.
The earliest reliable history of P. Semilanceata intoxication dates back to 1799 in London, when a family prepared a meal with mushrooms they found growing in London's Thames park. In the early 1950's it was the first European species confirmed to contain psilocybin. In current times, it is more commonly known as "Liberty Cap". P. Semilanceata grows in a much more diverse range of environments than most of its relatives in the Psilocybe genus, allowing it to spread prolifically from its speculated original habitat in Europe to nearly every continent. Results from testing done by Stamets and Gartz in 1997 place it as the third most potent Psilocybe species.
Psilocybe Semilanceata is on average the smallest of the 4 prominent Psilocybe species, and one of the most potent. Like all mushrooms of the Psilocybe genus, they have a hygrophanous nature, meaning their coloration shifts depending on hydration levels. They turn a bluish color when handled or bruised, due to the oxidization of psilocin. The underside of the pileus is densely gilled, and they possess a thin gelatinous veil (pellicle) separating the pileus and stipe. This veil leaves an annular zone on the stipe that may be darkened by spores.
Pileus (caps) range from 5–25 mm in diameter and 6–22 mm tall. Caps vary in shape from sharply conical to bell or spear shaped with translucent striated margins. Comparative to other psilocybe species the pileus does not change shape considerably as it ages, however is more hygrophanous. When fresh coloration is chestnut brown to pale brown, fading to light yellowish-white-tan when dry.
Lamella (gills) are narrow and moderately spaced underneath the cap, their color is pallid early in the fruiting period, but quickly becomes brownish and by maturity is a purplish brown, often with the edges remaining pallid.
Stipe (stem/stalk) is generally between 40-100mm long and 0.75-3mm thick, flexible, mostly cylindrical and pliable. Its surface is smooth and silky, coloration is frequently pale, becoming discoloured brown or tan near the base, which also commonly has blue tinged mycelium attached.
Spores are deposited as a dark gray and transform to purple-brown with a lighter edge when fully mature. Spore print is an ellipsoid measuring 12-14 x 7-8 micrometers.
Psilocybe Semilanceata have a farinaceous (similar to freshly ground flour) odor and taste.
Psilocybe semilanceata fruits solitarily or in groups in rich and acidic soil, typically in grasslands, such as meadows, pastures, or lawns. It is often found in pastures that have been fertilized with sheep or cow dung, although it does not typically grow directly on the dung. These environments are spread plentifully across the globe, meaning that P. Semilanceata are found growing in numerous countries on varied continents.
Some of these countries include Austria, Belarus, Belgium, Bulgaria, Czech republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Australia, New Zealand, Canada, the United States, Chile, the Netherlands, Norway, Poland, Russia, Spain, Sweden, Switzerland, Turkey, the United Kingdom, Ukraine, India, and Pakistan. It is considered the most widespread psilocybin mushroom.
One danger of attempting to consume hallucinogenic or other wild mushrooms, and why it should be left to experienced mycologists, is the possibility of misidentification with toxic species. Liberty caps are easily misidentified for the poisonous Psathyrella species. The primary identifying difference is the slimy cap of the Semilanceata, whereas the Psathyrella exhibits a silky film on its cap.
Another pertinent note regarding Semilanceata is that Laboratory tests have shown it to suppress the growth of the soil-borne water mold Phytophthora cinnamomi, a virulent plant pathogen that causes the disease root rot.