The Herbarium of the Arnold Arboretum (A) contains more than 1.3 million pressed plant specimens, and is maintained at the Harvard University Herbaria (HUH) in Cambridge, MA. The combined holding at HUH—numbering some 5 million specimens—represents one of the largest and most valuable resources for studying plant diversity in the world. The Herbarium of the Arnold Arboretum (A) is especially strong in material from Indo-Malesia (India to the Philippines and Papuasia), China, and eastern and southeastern Asia. The Chinese and Philippine collections are as comprehensive as any in existence. The Arboretum and Harvard University Herbaria also serve as one of the five editorial centers in the western hemisphere for the Flora of China project.
The Arboretum collection is also rich in type specimens, which are essential to the formal naming and description of their species. The Arboretum’s type specimens largely result from the work of staff members such as R. A. Howard, I. M. Johnston, C. Kobuski, E. D. Merrill, E. J. Palmer, A. Rehder, C. S. Sargent, C. K. Schneider, and E. H. Wilson. Several special collections reflect the interests of former staff members; these include the McKelvey Agave and Yucca spirit collection (recently rehoused in compactor storage units in Cambridge), and the Shaw collection of the genus Pinus.