Foraging in London

Know these first

What can hurt you around London in October

14 species on our hazard list have been recorded near here this month, 6 of which can kill a healthy adult. Learn these before you learn anything you intend to eat.

• Can kill229 records nearby

  Ragworts and groundsels (Senecio)

  Senecio (the whole genus)

  Mistaken for

  Wild greens and herbal teas — and, in the past, home-grown wheat: Senecio in the flour poisoned whole families in South Africa's George district in 1918.

  How to tell

  Daisy-family plants with yellow flower heads (with or without petals), each head wrapped in a single row of narrow green bracts, often black-tipped, and seeds carrying white fluffy parachutes. A yellow daisy you can't name does not go in the pot.

  What it does

  Pyrrolizidine alkaloids, which baking does not destroy. They block the small veins of the liver (veno-occlusive disease): pain, a swollen liver and fluid in the belly, and in many cases cirrhosis. Children are the most vulnerable.

• Can kill107 records nearby

  Yew

  Taxus baccata

  Mistaken for

  Its sweet red arils look like berries, and it lines churchyards, parks and hedges where foragers pick spruce tips and juniper.

  How to tell

  Flat, dark green needles in two rows, plain green underneath with no white stripes, and red fleshy cups open at one end with a hard seed showing. No cones, no resin smell.

  What it does

  Taxine alkaloids stop the heart. The needles and the seed inside the red flesh are poisonous, there is no antidote, and about 50 g of needles can kill an adult.

• Can kill

  38 records nearby

  Brown roll-rim

  Paxillus involutus

  Mistaken for

  Assorted brown gilled mushrooms; it was eaten as an edible in Europe for generations.

  How to tell

  Inrolled felty cap margin, gills that bruise dark brown and can be rubbed off the cap, growing under birch.

  What it does

  Sensitises the immune system over repeated meals, then one day triggers it to destroy the eater's own red blood cells. People have died after eating it safely for years.

• Can kill

  28 records nearby

  Poison hemlock

  Conium maculatum

  Mistaken for

  Queen Anne's lace, wild chervil, cow parsley and garden parsley.

  How to tell

  The stem is hairless, smooth and blotched with purple, and the crushed leaves smell musty and unpleasant — some say of mouse. Queen Anne's lace has a bristly-hairy green stem and smells of carrot.

  What it does

  Paralysis that climbs from the feet until breathing stops, with the mind clear throughout. This is what killed Socrates.

• Can kill

  21 records nearby

  Death cap

  Amanita phalloides

  Mistaken for

  Paddy straw mushrooms, young Agaricus, and anything picked as a 'field mushroom'.

  How to tell

  Greenish to olive cap with a faint metallic sheen, white gills, a ring, and a sac-like volva at the base. Introduced with European trees and now widespread, especially under oaks.

  What it does

  Responsible for most fatal mushroom poisonings worldwide. Half a cap can kill an adult; symptoms start only after the damage is done.

• Can kill18 records nearby

  Thorn apple (Datura)

  Datura (the whole genus)

  Mistaken for

  Young plants come up among amaranth (morogo) and other wild greens in maize fields and gardens, and children eat the seeds.

  How to tell

  A coarse, rank-smelling plant with large, irregularly toothed leaves, big upright trumpet flowers, white or purple, and a spiny, walnut-sized capsule packed with small dark seeds. Amaranth has smooth-edged leaves and only bristly flower spikes.

  What it does

  Atropine and scopolamine: dry mouth, hot flushed skin, a racing heart, huge pupils, then delirium and hallucinations that can last a day or more. It has killed adults and children.

• Hospital

  571 records nearby

  Fly agaric

  Amanita muscaria

  Mistaken for

  Rarely mistaken once it is open — but the buttons, before the cap expands, look like white eggs and get picked as puffballs.

  How to tell

  Cut any 'puffball' in half. Solid white all the way through is a puffball; the outline of a cap, gills and stem inside is an Amanita button.

  What it does

  Ibotenic acid and muscimol: nausea, then confusion, agitation and deep sedation for several hours. Not usually fatal, but genuinely dangerous in children.

• Hospital

  283 records nearby

  Sulphur tuft

  Hypholoma fasciculare

  Mistaken for

  Honey mushrooms and other autumn clusters on stumps.

  How to tell

  Sulphur-yellow to greenish gills and a bitter taste on the tip of the tongue. Honey mushroom has white to cream gills and a white spore print.

  What it does

  Prolonged vomiting; in quantity it has caused liver damage.

• Hospital

  127 records nearby

  Bittersweet nightshade

  Solanum dulcamara

  Mistaken for

  Its red berries get picked as currants or tomatoes by children.

  How to tell

  Purple flowers with a yellow beak, leaves with a pair of small lobes at the base, and berries that ripen green to orange to red on the same cluster.

  What it does

  Solanine: burning throat, vomiting, and in a child, worse.

• Hospital126 records nearby

  Euphorbias (milk bushes, naboom, pencil tree)

  Euphorbia (the whole genus)

  Mistaken for

  Prickly pear and other cacti — many African euphorbias are spiny, leafless succulents that look exactly like cacti — and the pencil-stick hedges of Euphorbia tirucalli around farms and villages.

  How to tell

  Break a stem: a euphorbia bleeds white milky latex at once. Cacti such as prickly pear bleed clear or slimy sap, and their spines grow from small fuzzy cushions; euphorbia spines grow singly or in pairs, never from a cushion.

  What it does

  The latex burns skin and mouth, and in the eye can cause temporary blindness. Wear gloves and eye protection near a cut plant, and never rub your eyes.

• Hospital

  48 records nearby

  Common earthball

  Scleroderma citrinum

  Mistaken for

  Puffballs — it is round and it is on the ground.

  How to tell

  Cut it. An earthball has a thick hard rind and turns purple-black and marbled inside very early. An edible puffball is soft and pure white throughout, like a marshmallow.

  What it does

  Violent gastrointestinal illness; the spore dust irritates the lungs.

• Hospital18 records nearby

  Yellow stainer

  Agaricus xanthodermus

  Mistaken for

  Field, horse and wood mushrooms — about half the poisonings among people who gather Agaricus mushrooms are this one.

  How to tell

  Scratch the cap edge or cut the base of the stem: it turns an instant, bright chrome-yellow that later fades brown, and smells of ink or carbolic soap — more strongly as it cooks. Edible field and horse mushrooms smell pleasant and yellow only slowly and faintly, if at all.

  What it does

  Sweating, flushing, severe cramps, vomiting and diarrhoea. Some people eat it without trouble, which keeps its reputation muddled; it is banned from sale in Italy.

• Hospital

  15 records nearby

  Panther cap

  Amanita pantherina

  Mistaken for

  The blusher and other brown Amanitas some foragers eat.

  How to tell

  Brown cap with white warts, a ring, and a distinct rim at the top of the bulbous base. The blusher stains pink-red where damaged; this does not.

  What it does

  A stronger dose of the same compounds as fly agaric, with more hospital admissions and occasional deaths.

• Unpleasant

  36 records nearby

  Buttercups

  Ranunculus (the whole genus)

  Mistaken for

  Young greens gathered in damp meadows, and marsh marigold.

  How to tell

  Glossy five-petalled yellow flowers; the leaves are acrid and burn the tongue when tasted raw.

  What it does

  Blisters the mouth and skin. Cooking destroys it, which is why marsh marigold is always boiled.

These are recorded within about 40 km of here in this month, from verified public observations. It is not a complete list of what is dangerous — nothing is — and a species missing from it may still be in your woods. Never eat anything identified from a photograph and a description alone.