Native to (or naturalized in) Oregon:
- Broadleaf deciduous tree, grows rapidly at first than slows, mature height 50-60 ft (15-18 m) high and a spread of 25-40 ft (7.5-12 m) wide, vase shaped, forming long arching branches; in appearance it resembles the American Elm, but is slightly smaller. Leaves alternate, simple, 3-10 cm long, 2.5-5 cm wide, about 12 pairs of veins, base asymmetrical, margin doubly serrate, upper surface lustrous dark green and smooth; with good sun exposure fall color is bright yellow. Fruit is a disc-shaped samara, rounded, notched, about 1 cm long, greenish, but may have reddish tinge, fringed with hairs.
- Sun to partial shade. Reportedly tolerant of Dutch elm disease, elm leaf miner and elm leaf beetle.
- Hardy to USDA Zone 4 ACCOLADE™ (cultivar name, 'Morton') was derived from a tree planted at the Morton Arboretum, in Lisle, Illinois, many years ago, the tree became known as the Thornhill elm because it is next to the Thornhill Education Center at the Arboretum. The Thornhill elm apparently originated from seed collected in 1924 from a tree at Harvard's Arnold Arboretum in Massachusetts. The Thornhill elm is a large tree and is similar in appearance to the American elm (Ulmus americana), but it is in fact considered a hybrid of Japanese elm (Ulmus japonica and Wilson's elm (Ulmus wilsoniana). The splendid habit and glossy dark green leaves of the Thornhill elm inspired the elm improvement program at the Morton Arboretum under the direction of Dr. George Ware, Research Dendrologist. In the Flora of China, Ulmus japonica is now classified as Ulmus davidiana var. japonica and Ulmus wilsoniana as Ulmus davidiana var. davidiana.
- Oregon State Univ. campus: SW corner of Valley Library.