Several old monasteries and castles have medicinal or poison gardens and one of the most famous is at Alnwick Castle better known as the location for Hogwarts in the Harry Potter films.
Poison Garden is a fantastic website from John Robertson the former Poison Garden Warden at Alnwick. It includes a vast amount of information, much of it gleaned while he was researching plants to be planted in the garden there.
Whilst many wild plants and flowers are edible some are extremely poisonous. Aconite in the picture above is also known as monkshood and is very toxic – it has very pretty purple flowers and is commonly found in gardens – the picture above was taken in a council car park!
Aconite is used in herbal medicine in many parts of the world and widely used in homeopathy but never, ever try and make your own medicine from the fresh plant.
The Poison Garden website has an excellent A to Z of poisonous plants as well as many short videos like the one above with key identification points, folklore and uses of some of the plants.
Many poisonous plants have a great deal of folklore or old stories attached and if you would like to find out more about that sort of thing I highly recommend Dangerous Garden: The Quest for Plants to Change Our Lives. David Stuart has crafted a fascinating and engaging read full of stories of poisonings, plague, medicines, mass hysteria and a wonderful insight into the role poisons play in our lives. Click on the image below and it will take you to the book on Amazon – however, I quite understand many peoples have issues with Amazon and prefer to shop elsewhere. If so, have a look at Alibris UK which is like Amazon but nicer and full of independent booksellers.