Pliny the Elder describes a now-lost illustrated herbal by Crateuas, a book that united pharmacological descriptions of plants with their illustrations. Pliny is skeptical about an illustrator’s ability to copy nature precisely enough for a reader to make a correct and safe identification of medicinal plants. Galen, too, issues caution and notes that descriptions may be helpful to remind readers about a particular plant, but as a means of transmitting knowledge for identifying such materials, it is simply too dangerous; some things are best studied directly from nature. None of Galen’s pharmacological books include pictures, but the practice of illustrating pharmacopoeia continued, and many herbal manuals from the ancient world did include images ranging in style from elegant to cartoonish. The earliest known extant example of an illustrated herbal, the "Johnson Papyrus," dates to 400 CE and offers a clear case in point for Pliny’s apprehension regarding these illustrations. The representation of “phlommos,” or mullein, is likely drawn from an earlier picture of the plant rather than from nature (one clue is that the plant does not grow naturally in the Nile valley, the papyrus’s place of creation). Yet illustrated herbals proved useful to scientists nonetheless, and they continued to be produced even into the twelfth century CE.
Dioscorides’s text, however arranged or rearranged, remained in use through the nineteenth century. One of the most famous of these editions, the Byzantine-era Vienna Dioscorides parchment manuscript, includes 383 illustrations, and while a fair number of these plant and animal pictures show a high degree of naturalism, others are far more abstract and interpretive. Scholars today believe that this illustrated edition was also likely modeled on earlier examples of herbals rather than drawn primarily from plant samples in life, and later herbal manuscripts reveal an extension of this illustration tradition.