Where and when liberty caps grow

The liberty cap grows in grassland: pastures, hay meadows, parkland and old lawns, most often where the soil is poor or acidic and has not been enriched with artificial fertiliser. In Britain and Ireland it appears in summer and autumn. It is a decomposer that lives on dead and dying grass roots, which is why it comes up in turf and never on wood.

A fungus of grass roots

Most of the liberty cap's life is spent as a network of fine threads in the soil. Studies published in 1989 and 1990 by Susan Keay and Averil Brown found the fungus colonising the roots of common pasture grasses, including bent (Agrostis), annual meadow-grass (Poa annua) and perennial ryegrass (Lolium perenne) (Keay and Brown 1990). The mushrooms are only the short-lived fruiting bodies of that network.

The species is often found in fields grazed by sheep or cattle. That has led to the common belief that it grows on dung. It does not: unlike Psilocybe cubensis, a tropical species that does grow directly on dung, the liberty cap feeds on decaying grass roots (species account).

Grassland that has been left alone

The British mycology site First Nature describes the liberty cap as most common on upland pastures, particularly hill slopes, and on pasture and parkland that has not been enriched with artificial fertiliser (First Nature).

Wood chip mulch, compost and stumps are a different habitat. They support Galerina and Pholiotina species with amatoxins. Where a lawn meets a flower bed or buried wood, the two groups can fruit within a few metres of each other, which is one reason the lookalikes are a real hazard.

Season

Fruiting depends on rain and temperature, so dates vary from year to year and from valley to hill. Mushrooms of many other species come up in the same weeks, including the brown mottlegill and the milky conecap on lawns.

Range

In 1983 the Mexican mycologist Gastón Guzmán called the liberty cap the most widespread psilocybin mushroom in the world, then known from 18 countries; records have grown since. It occurs throughout Europe, across Canada from British Columbia to Newfoundland, in the Pacific Northwest of the United States, and in Australia, where it may have been introduced, and New Zealand, where it grows in high grasslands (species account).

In Britain and Ireland it is described as fairly frequent but rather localised. Records are mapped by the NBN Atlas for the UK and by the National Biodiversity Data Centre for Ireland. These maps show where the species has been recorded by naturalists. They are records for science, and they say nothing about access or legality.

What the habitat means legally

Liberty caps can come up on farmland, in parks, in gardens and on verges. In the UK, mushrooms that are simply growing wild on land are not an offence for the owner: the law makes an exception for a fungus that is "growing uncultivated". Picking one to keep or to use is possession of a Class A drug. Picking one only to destroy it, or to hand it to someone lawfully entitled to take it, is also covered by an exception. The law entry explains the regulations and the Dutch position.

What to read next

See the field characters for how the species is described, and lookalikes for the species that share its season. The history entry tells how a family in London's Green Park came across it in 1799.