Founded in 1908, the Joseph F. Rock Herbarium (HAW) serves the official university repository for botanical plant specimens and includes the Lyon Arboretum specimen collection. It is the result of decades of plant exploration by some of the leading researchers in the Pacific basin and collections continue to expand. Today, the herbarium is part of the University Museum Consortium, and comprises approximately 50,000 dried preserved plant specimens.

Mission: The mission of the herbarium is to maintain and expand the collection to make a thorough representation of Hawaiian and Pacific Island flora, with particular emphasis on vascular plants. For more than 100 years, the herbarium has been a focal point for teaching, training, and education on the flora of Hawai'i and the Pacific.