Liberty cap lookalikes: toxic species compared

The mushrooms most often confused with the liberty cap are small, conical and brown or white, and several of them are dangerous. Some contain amatoxins, the same liver toxins as the death cap. One contains orellanine, which destroys the kidneys. Others contain muscarine or have never been properly tested. This entry compares them and summarises published cases where people looking for liberty caps ate something else.

Why confusion is so easy

Grassland fungi are small, numerous and variable, several species fruit in the same weeks of late summer and autumn, and their caps change colour as they dry. Most of the dangerous lookalikes do not look alike in a field guide photograph. They look alike in wet grass at dusk, half-dried in a pocket, or after handling.

Amatoxin poisoning makes the mistake worse because it is slow. Symptoms usually begin more than six hours after the meal, as severe stomach upset, and liver failure can follow (Parant et al. 2006). Mushrooms containing amatoxins are behind about 95 percent of deaths from mushroom poisoning worldwide (Horowitz and Moss, StatPearls).

The species compared

Species	Where it grows	Cap	Spore print	Toxin
Liberty cap, Psilocybe semilanceata	Unfertilised grassland, pasture, among grass roots	0.5 to 2.5 cm, sharply conical with a nipple	Dark purple-brown	Psilocybin (Class A in the UK)
Funeral bell, Galerina marginata	Stumps, dead trunks and fallen branches	1 to 7 cm, rufous brown fading to honey	Snuff brown	Amatoxins, potentially lethal
Pholiotina rugosa (Conocybe filaris)	Wood chips, flower beds, compost	Under 3 cm, conical with a central bump	Rusty brown	Alpha-amanitin, potentially lethal
Milky conecap, Conocybe apala	Lawns, parks, golf courses	0.8 to 1.5 cm, sharply conical, milky white	Rust brown	Untested; treated as suspect
White fibrecap, Inocybe geophylla	Path edges and verges under broadleaf trees	1.5 to 3.5 cm, conical with a pointed bump, white	Dull brown	Muscarine
Brown mottlegill, Panaeolina foenisecii	Lawns and verges, April to December	1 to 2 cm, bell-shaped, brown drying to beige	Dark brown	Inedible; children have become ill
Deadly webcap, Cortinarius rubellus	Wet conifer and mixed woods, among moss	2.5 to 8 cm, conical to convex, tawny	Rusty brown	Orellanine, kidney failure

Sources for the table: First Nature for Galerina marginata, Conocybe apala, Inocybe geophylla and Panaeolina foenisecii; Hallen et al. 2003 for amatoxins in Conocybe filaris; the species account of Pholiotina rugosa and of Cortinarius rubellus.

Galerina: the amatoxin genus

Galerina species are small and brown, and several contain amatoxins in amounts that can kill. Clinical references list Galerina autumnalis, G. venenata and G. sulcipes alongside the death cap (StatPearls). The best known in Britain, the funeral bell, grows on wood, which separates it from the liberty cap by habitat. That separation only holds if the collector knows what the mushroom was growing on, and buried wood in a lawn is invisible.

The North American Mycological Association's poisoning registry recorded "a Psilocybe seeker who apparently consumed Galerina by mistake and may have suffered some liver damage", and noted that a similar mistake years earlier "cost another young person her life" (NAMA Toxicology Report 2010).

Pholiotina and Conocybe: conecaps of lawns and mulch

Conecaps are fragile, long-stemmed and pointed, and many grow in short grass. Pholiotina rugosa, also published as Conocybe filaris, contains alpha-amanitin and grows in wood chips, flower beds and compost, the edges of exactly the lawns and parks where grassland species appear. It has a movable ring, but that ring is fragile. The milky conecap is a common lawn species after rain; it has not been shown to be deadly, but First Nature advises treating it as suspect because related species carry amatoxins (First Nature).

Inocybe: fibrecaps and muscarine

Fibrecaps have conical caps with a pointed bump and silky, fibrous surfaces. The white fibrecap contains muscarine; salivation and heavy sweating usually start within half an hour, followed by stomach pain, blurred vision and in serious cases laboured breathing (First Nature). Many other fibrecaps are brown and conical, and they grow along woodland edges next to grass.

Mottlegills and other dark-spored grassland species

The brown mottlegill is a common small brown mushroom of British lawns and verges. Its gills are mottled because patches ripen at different times, and its print is dark brown. Some collections contain traces of psilocybin, almost certainly too little to have any effect, and children have become ill after eating it (First Nature). Because its spore print is dark, it slips past the spore print test that excludes Galerina and Pholiotina.

Cases where the mistake was made

Austria, 1996. A young man who had gone looking for liberty caps ate the deadly webcap, Cortinarius rubellus, and developed end-stage kidney failure (Franz et al. 1996). Orellanine poisoning is particularly deceptive: the first symptoms usually take from two to fourteen days to appear (orellanine).
North America, 2010 registry. A collector looking for Psilocybe ate Galerina by mistake, with probable liver damage (NAMA, above).
Poland, review of 2010. Toxicologists in Łódź wrote that websites make mushroom pictures easy to find, and that this leads inexperienced pickers to misidentification, "frequently" with fatal results (Marciniak et al. 2010).

If someone has eaten a wild mushroom and feels unwell, call NHS 111 or 999 in the UK, or 112 in the Netherlands, and keep any leftover mushrooms for identification. Delayed vomiting or diarrhoea six hours or more after a wild mushroom meal is an emergency even if the person feels better afterwards.

What to read next

The field characters entry explains which features mycologists rely on and where they fail. The habitat entry shows why these species turn up together, and the chemistry entry covers what is known about the liberty cap itself.