Take a walk down any street in the urban core of Washington, D. C. and you’re likely to encounter majestic elms that contribute a great deal to the cooling shade and beauty of our capital city. Although many have been lost to Dutch elm disease over the years, newer plantings of disease resistant cultivars assure the city of a shady future.
Among the elms that grace the quadrant of the Mall that connects the Capitol with the Washington Monument is the Jefferson Elm, a towering tree that’s distinctive for its dark green foliage, classic American elm form, and resistance to Dutch elm disease. It grows along Jefferson Drive near the Freer Gallery of Art. Cared for by the National Park Service, it is among several hundred elms planted in the 1930’s in two double rows along the National Mall.
The magnificent Jefferson Elm was identified and championed by the late James Sherald, plantsman, plant pathologist and public servant. Decades ago, we had the good fortune to work closely with Jim and the National Park Service and the U.S. National Arboretum in bringing the Jefferson Elm to market. New Plant Development Director Keith Warren, now retired, trialed the tree for years to make sure it was superior to other elms and determined that it could be successfully propagated.
Released by the National Arboretum in 2005, we were among the first to offer the tree to the trade in 2010. It has since become a favorite among the disease-resistant American Elms. A recent edition of The Leaflet, published by Casey Trees, tells the story of James and the Jefferson Elm.
Jefferson Elm
Ulmus americana ‘Jefferson’
Deep green foliage and an upright vase shape characterize this fine American Elm. Open, U-shaped branch unions, arching limbs and an upright vase shape make it easier to manage in the nursery and the landscape. Leaves deepen to dark green earlier in spring and hold their dark color longer in the season than is typical of the species. Fall color is bright yellow. Tested and shown to be highly tolerant of Dutch elm disease, this joint introduction of the U. S. National Arboretum and the National Park Service is noted to be “generally sterile” on the USNA fact sheet. A verified triploid, it typically produces little to no seed.
Valley Forge Elm
Ulmus americana ‘Valley Forge’
Selected by USDA researchers after 20 years of research, this U. S. National Arboretum introduction has tested best for Dutch Elm Disease tolerance, bringing hope for the return of the American Elm. Fast growing but a little wild in the nursery, with timely, regular pruning in the nursery it matures to form a stately shade tree with a vase shaped crown. Mature height and spread are approximately 70’ x 70’.
New Harmony Elm
Ulmus americana ‘New Harmony’
Introduced by the U.S. National Arboretum, this handsome tree features the classic vase shape of the American elm along with a high level of disease tolerance. A vigorous grower, it matures with a somewhat narrow canopy as it reaches a height and spread of 70’ x 65’.
Originating from a seedling selection made at the USDA research facility in Delaware, Ohio, according to a USNA fact sheet, it was second only to Valley Forge Elm in its tolerance of Dutch elm disease. Balanced growth and a little slower growth rate recommend it as a more manageable tree in the nursery and the landscape than the ultra-tolerant Valley Forge.
Like other American elms, New Harmony Elm tolerates poor soil conditions, drought, deicing salts, air pollution and a wide range of pH levels. Released by the U.S. National Arboretum in 1994, it was first offered by our nursery in 2011.
According to a 2015 i-Tree Ecosystems analysis, although elms make up just 2% of the District’s tree canopy of more than 2,431,000 trees, they play an outsize role in shading the Capitol grounds. Around the city, elms planted in residential and commercial streetscapes contribute to cooler, healthier neighborhoods. The extensive planting of American, Asian and hybrid elms over the past couple of decades has surely increased this percentage. Currently, we offer 18 pest and disease-resistant elm cultivars that contribute to the species diversity of urban forests across North America.
Prairie Expedition® Elm
Ulmus americana ‘Lewis & Clark’
This Plains-tough American native descends from a lone survivor of Dutch Elm Disease found along the Wild Rice River near Fargo, North Dakota. Named in honor of the 1803 exploration of the West led by Meriwether Lewis and William Clark, it was trialed and introduced by North Dakota State University.
Fast growth of the broad spreading, vase shaped canopy delivers quick shade in cold prairies and harsh urban environments. Extremely cold hardy through USDA Zone 2b, this noble tree matures to a height and spread of approximately 55’ x 60’.
Colonial Spirit® Elm
Ulmus americana ‘JFS Prince II’
A strong and manageable branch structure distinguishes this selection of American elm in both the nursery and the landscape. Selected by the historic Princeton Nurseries of New Jersey, it has proven Dutch Elm Disease tolerant by surviving controlled testing. Growing to a height and spread of 65’ x 50’, its hardiness is USDA Zone 4. Arching branches of this symmetrically vase shaped tree broaden with age to reveal a classic American Elm shape.
Accolade® Elm
Ulmus japonica x wilsoniana ‘Morton’
Probably the best known of the hybrid elms developed by Dr. George Ware at Morton Arboretum, the parent tree stands tall on the arboretum grounds. An introduction of Chicagoland Grows®, it has a vase-shaped habit with upright arching stems reminiscent of the American elm. Accolade® elm has proven to be a robust and vigorous grower, and is also valued for its fine-textured, dark-green glossy foliage, and yellow fall color. This selection has very good resistance to Dutch elm disease and elm yellows and is also highly resistant to elm leaf beetle. Accolade® elm is a chance seedling selection from The Morton Arboretum collections.
Triumph™ Elm
Ulmus x ‘Morton Glossy’
Triumph™ Elm has and upright branching habit that is easier to train as a young tree, making it a favorite of growers and tree planters. Attractive deep green foliage turns yellow in autumn. Upright oval in youth, it becomes more vase shaped as it matures to a height and spread of 55’ x 45’. It resists diseases and pests including Dutch elm disease and elm yellows and has moderate resistance to elm leaf beetle and Japanese beetle. Hardiness is USDA Zones 4-9.
The second cultivar introduced by Chicagoland Grows® from Dr. George Ware’s elm improvement program at Morton Arboretum, this outstanding hybrid resulted from a controlled cross of Accolade® and Vanguard™ elms.
Gardeners! Please note that our nursery is strictly wholesale. To purchase these and other trees grown by our nursery, please use our Retailer Locator to find sources of JFS trees near you.
