Foraging in Reykjavík

Know these first

What can hurt you around Reykjavík in October

4 species on our hazard list have been recorded near here this month, 1 of which can kill a healthy adult. Learn these before you learn anything you intend to eat.

• Can kill7 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.

• Hospital

  1 record 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

  1 record nearby

  Giant hogweed

  Heracleum mantegazzianum

  Mistaken for

  Cow parsnip and angelica, both of which are eaten.

  How to tell

  Enormous — three to five metres — with a stem thicker than a wrist, bristly and blotched with dark purple, and umbels the size of a dinner plate. Cow parsnip rarely passes two metres.

  What it does

  Sap plus sunlight burns the skin, with blisters and scarring that recur for years. In the eyes it can blind.

• Unpleasant

  1 record 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.