The Science Unit of the Botanical Garden includes a Herbarium, where the diversity of plants from El Charco del Ingenio and the San Miguel de Allende region is documented. It is an enclosure where collected plant samples (stems, roots, leaves, flowers and fruits of each species), pressed and dehydrated for their preservation and study, are protected and classified. Herbariums in the world function as information centers for the knowledge and conservation of plant diversity. The Herbarium of the Botanical Garden was accredited by the Mexican environmental agency (SEMARNAT) as a scientific collection in 2019, and bears the name of the prominent botanist Walter L. Meagher, in recognition of his contribution to the study of the flora of El Charco del Ingenio.