This selection is a lone survivor among American elm trees that died from Dutch elm disease along the Wild Rice River southwest of Fargo, ND. When inoculated with the Dutch elm disease fungus, this tree displayed high resistance. The original tree is still healthy and has continued to resist DED infection 15 years after the inoculation of clonal propagules was conducted. This selection produces dark-green foliage and develops the classic umbrella form which typifies American elm. Clonally-propagated trees planted under clean cultivation in NDSU trials averaged over 3' of growth annually for 10 years. The American Elm is North Dakota's State Tree and this selection was released and named for its apparent Dutch elm disease resistance in honor of the 200th anniversary of the Lewis and Clark Expedition in 2004. USDA hardiness zone 2b-3. Shelter, shade and boulevard tree. Available in nursery trade. Propagated by grafting, chip budding or cuttings. Hardiness: USDA hardiness zone 3-9 Mature Size: Height: 60', Spread: 40' Form (Shape): Umbrella-like form which typifies American elm. Growth Rate: Medium to Fast; NDSU trials averaged 3 – 4’ of growth annually over 10 years of evaluation. Foliage: Alternate, Simple, 3 – 6” long and 1 – 3’ wide; Summer: High quality lustrous dark green; Autumn: Yellow Texture: Medium Flower: Greenish-red fascicles of 3 – 4 (perfect), not showy Fruit: Rounded disc-shaped samara, not ornamental Special Features: DED resistant Light Preference: Full sun exposure Soil Preference: Prefers rich, moist soils but is highly adaptable to different soil types and pH. Propagation: Softwood stem cuttings Ornamental Attributes: High quality summer foliage. Landscape Attributes: Prairie Expedition® is an outstanding DED resistant American elm selection. Uses for this cultivar are in boulevard, park plantings and other large open spaces. Comments: Clonal trees were inoculated with DED and shown to be resistant to the disease. The original tree (pictured above) has a double leader, which makes the tree wider than what it would be if properly maintained as a single leader in the landscape. Patent Status: