(Radio Iowa) – An extensive botanical reference library that’s a growing resource for research has been on the Iowa State University campus for more than one-and-a-half centuries. The Ada Hayden Herbarium is home to nearly three-quarters of a million plant samples, according to curator Deb Lewis. She calls the herbarium a one-stop shop for studying Iowa’s native plants, as well as plants from all over the globe. Most of the herbarium’s holdings are plants that have been dried, pressed, labeled, attached to archival paper and stored for reference. Mounted and kept correctly, Lewis says they can last for centuries. The herbarium is housed in a complex of four adjacent interior rooms on the third floor of Bessey Hall. The samples are stored in about 250 large metal cabinets that are spread across the facility’s 43-hundred square feet.