Medicinal Plants. For the average person without easy or affordable access to doctors, many cures and preventatives were available through the tradition of the materia medica (medical matters), a survival of the late Roman world. This body of works describes hundreds of plants and their medicinal uses, as well as preventative regimens that were believed to lessen the chances of illness. In monasteries, palaces, and in most towns and villages "herbaria," or herb gardens, were kept to grow the vegetables, plants, and herbs used for medical treatments. They were generally laid out in a grid fashion, a trend begun by the influential Benedictine monastery of St. Gall in Switzerland during the ninth century. Many of the plants in the herbaria were ornamental as well as medicinal, and all were practical. Lilies not only look and smell good, but their roots were used...