A deadly plant has been discovered strewn across a Cornish beach in the aftermath of Storm Emma.

Cliff erosion in Porthkidney Beach, near St Ives, exposed poisonous Hemlock water dropworts - also known as dead man's fingers - with many of them falling onto the beach below.

The plants, which look and taste like parsley, have extremely toxic roots, which themselves resemble parsnips.

Josh Quick, a wild food expert who discovered the water dropworts, said it was the first time he had seen the roots exposed to such a degree.

“Whilst they are a beautiful plant, hemlock water dropwort is one of the most poisonous plants in the northern hemisphere and these roots are highly toxic,” he wrote on Facebook.

The forager warned anyone who ate them would be “dead tomorrow and today will be the worst day of your life”.

“They look a lot like parsnips and also smell fairly similar. Make sure nobody eats these and be careful with any dogs in the area. Looks like a lot more are going to fall soon,” he added.

“Again, these will kill you or your dog if eaten. A small portion of the leaves can kill a person and this is a plant every forager needs to be familiar with. The roots are the most toxic part and one of these roots is enough to kill a cow.”

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Mr Quick said the plants usually grew around water and riverbanks, and that it was “very unusual” to see them growing on cliffs.

Water dropworts contain the toxin oenanthotoxin, which attacks the central nervous system and causes the body to shut down.

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Leif Bersweden, botanist and PhD student at Kew Gardens, told The Independent it was "arguably the most toxic plant native to Britain" and that anyone who ate it would suffer convulsions, seizures and "definitely" die within 24 hours.

"The roots have a lot more of the toxin, the stem has a lot, and the leaves slightly less," he said. "But if you just touch the leaves and then eat a sandwich, say, then you’re going to get really ill."