Revealed: The deadly plants gardeners and foragers need to know about

From the poisonous yew to beautiful blooms and the garlic lookalikes with lethal powers, here's what you need to look out for

The toxic plant hemlock water dropwort. Pictures: Alamy

In pre-Roman times on the Mediterranean island of Sardinia, legend has it that Phoenician settlers used a poisonous plant called hemlock water dropwort for the ritual killing of elderly people and the execution of criminals.

The toxin caused the victim to grimace in a sinister sardonic smile brought on by a spasm in the muscle of the face, described in ancient Greek texts as "risus sardonicus", better known now as a rictus grin — but it was far from funny.