This collection contains plants that need the well-drained slopes and ideal conditions of the site. Many of these plants don't belong in any of the taxonomic collections on the grounds. There are some fascinating and unusual plants in this collection waiting to be discovered.
The Diversity Collection was started in 1950, and is displayed across a visually pleasing slope that offers protection for the unusual plants in this collection. It was established around the perimeter of an old gravel mine on the East Side. The soil at this site is very rich and well-drained, allowing plants that wouldn't normally perform well in other parts of the Arboretum to thrive here.
The collection contains over 120 different kinds of woody plants distributed across a relatively small area. They were planted here for a variety of reasons. Some require a special habitat, provided by the well-drained slopes or the "seep" (a place where groundwater rises to the surface). Others belong to small families for which there are no taxonomic collections on the grounds. Still others represent marginally hardy species that grow better here than elsewhere in the Arboretum.
Included in this collection is the Japanese coriaria (Coriaria japonica ) that is the sole representative of its family, Coriariaceae. This warm temperate native has flowers with berry-like swollen petals. Alabama snow wreath (Neviusia alabamensis) is a southeastern U.S. native and clump-forming shrub that produces flowers with numerous white stamens. Look for Wilson-tree (Sinowilsonia henryi ), an unusual members of the witch-hazel family. It is a monotypic genus, meaning there is only one species representing the genus. Its flowers are catkin-like long clusters of small green flowers. Also in this collection is the rare India quassia-wood (Picrasma quassioides), a plant native to Japan and Korea, and to northern India. It was traditionally used as an insecticide and a medicine due to the bitter quality of the wood.