The Morton Arboretum's Elm Collection is one of the most extensive collections of elm family plants (Ulmaceae) in the world. In addition to the elm genus (Ulmus), this collection also contains hackberry (Celtis), hemiptelea (Hemiptelea), and zelkova (Zelkova). The elms are the largest and most important part of the collection, due to their role in the Arboretum's elm breeding and distribution program.
The collection was started in 1926, making it one of the oldest taxonomic collections. It covers more than 5 acres in a park-like setting near the main entrance. Of the more than 75 different kinds, representing 167 specimens, many are mature spreading shade trees, making this collection a great year-round destination to visit, particularly in the warm summer months.
It is the elm's utility as a shade-tree that led to its popularity in the urban landscape. The American elm (Ulmus americana) was once very common along streets because of its rapid growth, vase-like shape, and adaptation to a variety of climates and soils. The introduction of Dutch elm disease all but wiped out this species.
The Arboretum's collection includes many rare Asian elm species that serve as an important gene pool for Arboretum scientists to develop and select hybrid elms resistant to Dutch Elm disease. Through the Chicagoland Grows®, Inc. Plant Introduction Program, the Arboretum has successfully introduced five new elm cultivars which has enabled the elm trees' return to the landscape. These include Accolade™ elm (Ulmus 'Morton'), Triumph™ elm (U. 'Morton Glossy'), Vanguard™ elm (U. 'Morton Plainsman'), Danada Charm™ elm, (U. 'Morton Red Tip'), and Commendation™ elm (U. 'Morton Stalwart').