Psilocybe semilanceata is a popular recreational mushroom known as the “Liberty Cap”. It gained its name from the characteristic Phrygian cap of antiquity, worn by those who occupied ancient Turkey, King Midas was one of their legendary leaders. While it has many characteristic traits, it is frequently confused for other members of Psilocybe and more commonly some toxic members of other genera.
It is considered a highly potent species which maintains its strength even after drying. Along with its nearly worldwide growth in the Northern Hemisphere, rarely found in the Southern Hemisphere, P. semilanceata is a common and popular mushroom. While levels of psilocin are usually low, this species frequently has amounts of psilocybin, baeocystin and norbaeocystin that place it in the top three most potent magic mushrooms.
The high levels of active compounds in P. semilanceata contribute to the blue-green tinge that develops with age. The bluing reaction to handling and damage, common among the other Psilocybe species, is subtle and variable in “liberty caps” and dependent on developmental state. The exception is P. semilanceata var. caerulescens, a nearly identical sub-species that commonly causes confusion.
Their vast range covering most of the Northern Hemisphere is most densely distributed in Europe. The oldest confirmed account of P. semilanceata was as early as 1799 in London, England; it was the first mushroom native to Europe identified to contain psilocybin. Human activity has since been beneficial to this species; its preferred habitat is in grassy areas where it gains its nutrients from decaying roots.
Found naturally in grasslands, meadows and amongst sedges, P. semilanceata prefers wetter areas with rich soils. While it shows a preference for fertilized fields, it does not grow directly on manure or dung. With a wide-ranging ecological preference and large distribution, this species is frequently encountered and confused with other species. Its characteristic features are so “generic” to Psilocybe, that it has been made the “lectotype” for the genus, the “prime specimen”.
The latin name of “semi-lanceata” literally translates to “somewhat-spear-shaped”, which quite accurately describes its shape. It has a conical or bell-shaped cap that frequently has a protruding tip known as a papilla. The spear reference is furthered with the base of young caps being rolled inwards toward the stipe. The edges have translucent striations when wet; the entire cap will be sticky to the touch with a separable, jelly-like pellicle.
These traits match many others in the Psilocybe genus, some species require a microscope to separate the two. P. pelliculosa is indistinguishable in appearance and has even been given the same nickname of “liberty cap”; P. strictipes is only different by lacking a papilla; P. mexicana, the “mexican liberty cap”, and P. samuiensis differ only by their natural ranges.
Further, P. semilanceata can be confused with other genera: Inocybe geophylla is a toxic (muscarine) species that shares most characteristics other than having a silky, rather than sticky, cap. The primary differentiating characteristic defining P. semilanceata is its non-straight stipe, often long and slender. They will frequently be bent, curved, angled or wavy; a straight stem is a rarity.
For the same reason that makes P. semilanceata widespread throughout Europe, its requirement for the decaying roots of grass makes indoor cultivation difficult. For the development of fruiting bodies, cultivation of grass or sedges are necessary alongside. This species does however form sclerotia somewhat readily, with the mycologist Gartz able to cultivate them in malt-agar surface culture.
Aside from any recreational, ceremonial or spiritual activities, P. semilanceata has also been implicated in the medical and agricultural domains. Researchers discovered that the species releases compounds that limit the growth of nearby bacteria, specifically those that compete with rotting roots for nutrients. While the specific compounds are unknown as of yet, extracts of P. semilanceata have shown promising results in the suppression of MRSA, a deadly bacteria frequently found in hospitals.
While its difficulty in home cultivation may make these mushrooms rare outside of wild finds, it is nonetheless a popular and well-known species. Identification may prove a challenge, but most twins of this species have psychoactive activity regardless. Aside from the known therapeutic usage of members of the genus, the new and effective control of bacteria with an unknown compound may open the door to expanded research on Psilocybe.