The idea that a plant’s appearance might give clues to its healing capacities is an old one (it was advocated by the Roman scholar Pliny the Elder). The word “signature” (from Latin “signare,” meaning ...

It’s hard to imagine being the first human being to look at a plant like, say, a stinging nettle and think, “I probably shouldn’t eat this, on account of the general agony it would cause me. But what ...

Among the documents are the notes of a 17th-century physician, who discusses his use of the doctrine of signatures to determine which medicinal plants to use for which ailments. "Lungwort (Pulmonaria) ...