About 30 important modern medicines, completely assessed by proper clinical trials, owe their origin in one way or another to plants. Sometimes, as with quinidine, the drug is actually contained within the plant, and on other occasions, as with amiodarone, it was investigation of a plant compound that led to the synthesis of a related, but better drug. So we may ask ourselves the question “How were the plants that yield good medicines discovered in the first place?” Quite often the answer is in folk medicine, long continued trial and error in the community having identified a plant such as the opium poppy as having useful healing properties. But folk medicine is not the only source. Valuable discoveries have been made from veterinary medicine, from large-scale screening programs of plant extracts, from observations by patients themselves, from physicians, and from research in organic chemistry. It is these last avenues of discovery that concern us here, because the local anesthetic action of cocaine was found during a psychiatric study, while lidocaine (lignocaine) was found from a chemical investigation of chlorophyll-defective mutants of barley...