The Arboretum's tree groups represent most of the prominent taxonomic groups of woody plant species found in temperate regions of the world. There are 42 taxonomic collections, grouped by plant genus (12), plant family (22), or other taxonomic grouping (8). The members in each group have genetically related features such as leaves, flowers, fruits, bark, twigs, and buds.
Putting related plant species in a collection is a useful practice, as it aids in the comparison and differentiation of traits within one kind of tree group. You can go to the oak collection, and see how an oak species from China is different from, or similar to, an oak species from the United States. This is a good way to learn how to identify trees, or to further your knowledge of a plant group by exploring the subtle differences between plants.
Often we have many different specimens of the same species, and this is another way to see how much variation can exist within just one species. Every white oak (Quercus alba) will not look exactly like every other, just like you look different from your neighbor even though you are 99.9 percent genetically identical.
Grouping plants in this way facilitates use for teaching, research, and evaluation.