When plants could cure, kill... or shock

Old folklore judged some plants medically beneficial because of their appearance, but the consequences could be dire, explains Ian Morton

- Ian Morton

FOR many centuries, the theory held that if some part of a plant resembled a human organ, then that plant could be used to treat the organ it resembled. At the heart of folk remedy and herbalism, this notion was nurtured throughout the classical world by respected medical scribes as far distant as Dioscorides (c40-90BC, Greek physician and botanist) and Pliny the Elder (cAD 23-79, Roman naturalist, author of Naturalis Historia, the role model for all encyclopedias). It gained theological credence in medieval times, and for a while was central to Western culture.

The doctrine of signatures

It was known as the Doctrine of Signatures. The 16th century Swiss physician Paracelsus declared that ‘Nature marks each growth according to its curative benefit’, and German religious mystic Jacob Boehme travelled a similar course with Signature Rerum (The Signature of All Things, 1621), which is said to have influenced Isaac Newton and Friedrich Nietzsche among others.

It resurfaced as recently as 2006 in the work of US author Elizabeth Gilbert whose best-selling Eat, Pray, Love was made into a film in 2010.

Looks determine healing merit

For want of better explanation, medieval medicine embraced the notion that the appearance of plants was a sign from the Almighty. Respected 17th century English botanist William Coles wrote of herbs in Adam in Eden, or Nature’s Paradise that: “The Mercy of God . . hath not only stamped upon them a distinct forme, but hath also given them particular signatures whereby a man may read the use of them”.