Capitulare de Villis by Charlemagne, the poem De cultura hortorum by Walahfrid Strabo and the Plan of St. Gall are some of the most comprehensive sources of information about the diversity of edible and medicinal plants in the 8 th-9 th century monastery gardens of West Europe. Examination of these sources reveals that the diet of the mediaeval European consisted of about 100 cultivated plants before the introduction of the now dominant staple plant species from the Americas.