In this textual comparison of seventeenth-century herbals, I show in detail that most of the descriptions and medicinal uses of English herbs included in Culpeper’s small folio The English Physitian (1652) and its enlargement of the following year were lifted straight out of the works of John Parkinson, apothecary. This was a deliberate act by Culpeper, to make available to the people of England the best information on native plant medicines for use in treating their illnesses. He attacked the College of Physicians of London, whom the great majority of the population could not afford to engage, for trying to keep this knowledge secret. Among later historians of the herbal tradition, Culpeper’s work was not accorded the same status as the great English herbals of William Turner, John Gerard, and John Parkinson, not because this borrowing was recognised but because its astrological content worked to divert attention from the quality and source of much of its guidance on treatment. Even contemporaries of Culpeper did not recognise the extent of the borrowing. Comparisons also reveal the limitations of Culpeper’s powers of plant description and his lack of interest in the developing science of botany. The editorial decisions Culpeper made to reduce a great folio herbal to a much smaller book to be sold for 3d touch on domestic and other non-medical uses, while points of discussion common to both authors such as the doctrine of signatures and superstitious beliefs about plants are explored.