Psilocybe semilanceata (Fr.) P. Kumm. - Magic Mushroom or LIberty Cap

Distribution - Etymology - Taxonomic History - Psychoactivity - Identification - Reference Sources

Psilocybe semilanceata - Magic Mushroom or Liberty Cap, Hampshire UK

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

Family: Strophariaceae

Psilocybe semilanceata, commonly known in the UK as the Magic Mushroom, and in the USA as Liberty Cap, appears in grassland in autumn. It is most commonly found on pasture and parkland that has not been enriched with artificial fertiliser.

Distribution

Fairly frequent in Britain and Ireland, where it is rather localised, Psilocybe semilanceata occurs throughout Europe and is found also in North America. (Picture left courtesy of David Kelly.)

Psilocybe semilanceata - Magic Mushroom or Liberty Cap, Bute, Scotland

Etymology

Psilocybe, the genus name, means 'smooth head' - a reference to the silkily mooth, scaleless surface of caps of these grassland mushrooms. The specific epitet semilanceata comes from semi- meaning 'half'and -lanceata which means 'spear-shaped'. Some of these little mushrooms do indeed look like spears, although many have wiggly stems uncharacteristic of spear shafts.

The common name Magic Mushroom is, of course, a reference to the hallucinogenic nature of this grassland species

Psychoactive alkaloid content

This species contains the toxin psilocybin. Because this substance, which occurs in Magic Mushrooms and several other related fungi, can cause alarming symptoms including vomiting, stomach pains and anxiety attacks, Psilocybe semilanceata should be treated as poisonous.

Psilocybe semilanceata - Magic Mushroom or Liberty Cap, seen in dry weather

It is our understanding that it is illegal to possess or to sell psilocybin in the UK. As of July 2005, fresh psilocybin mushrooms are now also controlled. They are treated in Law in the same way as dried magic mushrooms, because whether fresh or dried they have the same Class A drug status as Heroin, LSD and Cocaine.

Taxonomic history

This species was first described in 1838 by the great Swedish mycologist Elias Magnus Fries, who named it Agaricus semilanceatus. (Most of the gilled mushrooms were included initially in the genus Agaricus!) In 1871 German mycologist Paul Kummer transferred this species to the genus Psilocybe, renaming it Psilocybe semilanceata. Thev etymology of this name is based on physical features: the generic name Psilocybe means 'smooth head', while semilanceata means 'half spear-shaped'.

Identification guide

Cap of Psilocybe semilanceata, Magic Mushroom

Cap

Ranging from 0.5 to 2cm in diameter, the cream-coloured caps have striations that become more pronounced with age and in dry weather. The caps usually have a distinct pimple on the top.

Gills of Psilocybe semilanceata

Gills

The olive-grey free gills turn purple-black as the spores mature.

Cheilocystidia of <em>Psilocybe semilanceata</em>

Left: cheilocystidia (cystidia standing out from the gill edges) of Psilocybe semilanceata.

(Mouseover image to view a larger version of this photomicrograph.)

Stem of Psilocybe semilanceata

Stem

2 to 3mm in diameter and 4 to 10cm tall, the slender cream stem of Psilocybe semilanceata is fibrous, usually wavy and sometimes coloured blue towards the base.

Spores of Psilocybe semilanceata

Spores

Ellipsoidal, smooth, 11.5-14.5 x 7-9μm.

Spore print

Very dark purple-brown.

Odour/taste

Musty odour. Do not taste Psilocybe semilanceata because it is hallucinogenic, and some people have required hospital treatment after eating this species.

Habitat

This poisonous saprobic grassland mushroom is most often found on upland pastures, notably on hill slopes. Although sometimes seen on lawns and in lowland meadows it does not grow on dung.

Season

These so-called Magic Mushrooms can be found in Britain and Ireland throughout summer and autumn.

Similar species

Panaeolus semiovatus, the Dung Roundhead, is usually larger and does not have a pointed cap.

Panaeolina foenisecii, the Brown Mottlegill or Mower's Mushroom, is very similar in colour but is usually larger and does not have a pointed cap.

Psilocybe semilanceata - Magic Mushroom or Liberty Cap

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2011

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.