Psilocybe liniformans can cause confusion, as it has two distinct subspecies from two very different parts of the globe. Both contain psilocybin and trace baeocystin, resulting in a weak to moderate potency, though both display the common bluing reaction to damage and age that indicate the presence of psychoactive alkaloids.
The subspecies, or variants, are P. liniformans var. liniformans and var. americana. The former is one of the few Psilocybe mushrooms native to Europe, the latter is found in scattered areas of the Americas. Both have been anecdotally associated with allergic or negative reactions to consumption and should be approached with caution, especially for the first time.
Both variants of P. liniformans have a characteristic conic or convex cap that flattens with age, along with a slender stipe and the starchy scent and flavour common to the active Psilocybe. This, however, is where the similarities between the two species diverge, allowing for identification even from an unknown range.
P. liniformans var. liniformans is the bigger mushroom of the two: the glossy, red-brown cap grows as big as 8 centimetres; the grooved stipe that often displays a ring can be just as long (8cm). They are common throughout most of the Netherlands, more rarely in Belgium, Italy and Spain.
Their range is likely bigger than originally thought, as this subspecies is “coprophilic” or restricted to growing on or nearby the dung of horses or cattle, widespread in Europe and allowing for rapid increases in distribution. This preference, and many of the visible features of P. liniformans var. liniformans, are shared by P. coprophila. This related Psilocybe can only be differentiated by its distinct lack of a bluing reaction to damage or age.
P. liniformans var. americana is the compact variant of the species: the straw or gray-brown cap grows to only 3 centimetres and often has a broad, brown umbo. The stipe is equally tall (3cm) and frequently is covered with fine hairs or fibrils, becoming more common nearer the dark base. While never growing directly on dung, var. americana can be found nearby, preferring rich pastures and natural grasslands.
The americana variant is found scattered across its namesake, originally discovered in the Pacific Northwestern states of Washington and Oregon. It has since been collected in the state of Michigan and as far south as Chile. Due to the habitat flexibility, it is likely to be more widespread, with anecdotal evidence suggesting residence in the Canadian province of British Columbia.
Found on at least three continents and separated into two distinct variants, P. liniformans is one of the most widespread species of Psilocybe. While varying in habitat preferences and appearances, the similarities at their core bind the variants into one species. Due to the low potency and possibility for allergic reaction, P. liniformans has been historically avoided by amateur growers and is equally unavailable.
Stamets, P. E., et al. “A new species and a new variety of Psilocybe from North America.” Mycotaxon 11.2 (1980): 476-484.
Guzman, G., et al. “An emendation of Psilocybe liniformans, an uncommon species found in the Central Apennines (Italy).” Micol Veget Medit 21 (2006): 117-122.
Image found here.