To improve access to scientific literature, we have created Botanicus, a freely accessible, Web-based encyclopedia of digitized historic botanical literature from the Missouri Botanical Garden Library. We have been digitizing materials from our library since 1995, focusing primarily on beautifully illustrated volumes from our rare book collection. Botanicus has been supported by generous funding from the Institute of Museum and Library Services, the W.M. Keck Foundation, and the Andrew W. Mellon Foundation.