As much as herbs can heal, some can do harm. In this garden walk we will explore some of the more unusual plants that offer help and harm in equal measure. From aconite to arnica, pennyroyal to pokeroot, belladonna, foxglove and yew – these are the herbs we rightly respect but can cautiously use for specific cases and in specific doses. Not herbs for beginners but effective in the right hands and fascinating in their historic and ritualistic uses, as well as in their phytochemistry and pharmacological effects.