Never eat a wild mushroom identified only from a website, a book or an app. Have every find checked in person by an expert, such as a mycological society.
Identification
Chlorophyllum molybdites is a large, robust gilled mushroom. Young fruit bodies are egg-shaped, later opening to a broad, flat cap up to 30 cm across. The cap is white with a brownish central patch that breaks into scattered brown scales towards the margin. The gills are free and white at first, then slowly turn greyish green to olive as the spores mature, so young specimens can look completely white-gilled.
The stem is smooth and whitish, without the snakeskin banding of the true parasol, and carries a thick, movable double ring. The flesh is white and may turn slightly pinkish or reddish in the stem when cut.
The decisive test is the spore print: a cap left gills-down on white paper for several hours gives a green to greyish-olive deposit. Microscopically, the spores are large, thick-walled, ellipsoid and dextrinoid, with a germ pore. Because young caps may not yet print green, a white spore print from an immature specimen does not exclude this species.
Habitat and ecology
The green-spored parasol is a saprotrophic fungus of grassland and nutrient-rich soil. It appears on lawns, sports fields, pastures, parks and gardens, often in large fairy rings, mainly in summer and autumn after warm rain. It is widespread in tropical and subtropical regions worldwide and in warm temperate areas, including much of the eastern and southern United States, Mexico, Central and South America, South and South-East Asia, Africa and Australia.
It has been recorded in new areas outside its traditional range, probably helped by warm climates, irrigated lawns and transport of turf and soil.
Uses and importance
Chlorophyllum molybdites has no culinary use. Its importance lies in public health: because it grows in large numbers on lawns close to homes and resembles edible parasols and shaggy parasols, it is frequently eaten by mistake. It is often described as the most commonly eaten poisonous mushroom in North America, and poisonings are reported regularly from Asia and Australia.
The toxin has not been fully characterised; a high-molecular-weight protein has been suggested as responsible. Raw or undercooked specimens appear to cause more severe reactions, but cooked specimens have also caused poisoning.
For mycologists it is a textbook example of why spore print colour matters in identification.
Safety and edibility
The green-spored parasol is toxic and must not be eaten. Symptoms usually begin within roughly one to three hours and include severe nausea, repeated vomiting, abdominal pain and watery or bloody diarrhoea. Serious dehydration and low blood pressure can develop, especially in children, older people and people with other illnesses.
Anyone who has eaten this mushroom, or a parasol-like mushroom from a lawn that has not been reliably identified, should seek emergency medical help immediately, even before symptoms appear, and keep the remains for identification.
Never rely on a website, app or photo; have every wild mushroom checked in person by an expert such as a mycological society or a trained mushroom adviser. Children and pets playing on lawns where it grows should be supervised.
If you suspect mushroom poisoning, call your local emergency number or poison centre straight away, even before any symptoms appear, and keep the remains of the mushrooms.
Look-alikes
The true parasol (Macrolepiota procera) has a tall, slender stem with a snakeskin pattern, white gills and a white spore print, and grows mainly in woodland edges and grassland. The shaggy parasols (Chlorophyllum rhacodes and Chlorophyllum brunneum) have white spore prints, flesh that turns orange to red when cut and a bulbous stem base; Chlorophyllum brunneum also causes reactions in some people. Leucoagaricus leucothites is all white with a white print. Small white-capped Lepiota species and white Amanita species can be deadly, so any parasol-like mushroom needs expert confirmation.
Around the world
This species is mainly a problem of warm regions: the southern and eastern United States, Mexico, the Caribbean, South America, Africa, South and South-East Asia and Australia. Travellers and people who have moved from Europe, where parasols are popular edible mushrooms, are at particular risk of mistaking it for a familiar species.
