Lonicera, Magnolia, Malus, Quercus, Rhododendron, Syringa, Paulownia, Albizia, Ilex, Gleditsia and Tsuga. Other comprehensive collections include the Bradley Collection of Rosaceous Plants, the collection of conifers and dwarf conifers, and the Larz Anderson Bonsai Collection. Approximately 500 accessions are processed annually. The Index Herbariorum code assigned to Arnold Arboretum is A and it is used when citing housed specimens even after integration with Orchid Herbarium of Oakes Ames (AMES) and Gray Herbarium (GH). Collections policy The mission of the Arnold Arboretum is to increase knowledge of the evolution and biology of woody plants. Historically, this research has investigated the global distribution and evolutionary history of trees, shrubs and vines, with particular emphasis on the disjunct species of East Asia and North America. Today this work continues through molecular studies of the evolution and bio-geography of the floras of temperate Asia, North America and Europe. Research activities include molecular studies of gene evolution, investigations of plant-water relations, and the monitoring of plant phenology, vegetation succession, nutrient cycling and other factors that inform studies of environmental change. Applied work in horticulture uses the collections for studies in plant propagation, plant introduction, and environmental management. This diversity of scientific investigation is founded in a continuing commitment to acquire, grow, and document the recognized species and infraspecific taxa of ligneous plants of the Northern Hemisphere that are able to withstand the climate of the Arboretum's Jamaica Plain/Roslindale site. As a primary resource for research in plant biology, the Arboretum's living collections are developed, curated, and managed to support scientific investigation and study. To this end, acquisition policies place priority on obtaining plants that are genetically representative of documented wild populations. For each taxon, the Arnold Arboretum aspires to grow multiple accessions of known wild provenance in order to represent significant variation that may occur across the geographic range of the species. Accessions of garden or cultivated provenance are also acquired as governed by the collections policies herein. For all specimens, full documentation of both provenance and history within the collection is a critical priority. Curatorial procedures provide for complete and accurate records for each accession, and document original provenance, locations in the collections, and changes in botanical identity. Herbarium specimens, DNA materials, and digital images are gathered for the collection and maintained in Arboretum data systems and the herbarium at the Roslindale site. Research Research on plant pathology and integrated pest management for maintenance