Ulmus

Elm
Ulmaceae
Deciduous, Trees

Once highly prized shade trees, elms have fallen on hard times. Dutch elm disease (spread by a bark beetle) has killed millions of American elms in North America and can attack most other elm species. Many of the larger elms are appealing fare for various types of beetles, leafhoppers, aphids, and scale, making them time consuming to care for, messy, or both.

Ulmus americana

Native to eastern North America. This majestic, arching tree once graced lawns andstreets throughout its range, but it has been decimated by Dutch elm disease. Fast growthto 100 ft. or taller with nearly equal—sometimes greater—spread. Main branches upright,outer ones pendulous. Rough-surfaced, 3–6-in.-long, toothed dark green leaves; great variationin shade of yellow fall color. Leafs out very late where winters are mild. Pale green, papery seeds make a mess in spring.Disease-resistant varieties include ‘Princeton’ (upright, to65 ft. tall), ‘Valley Forge’ (vase-shaped, to 70 ft. tall), and ‘Jefferson’ (vase-shaped, to 70 ft. tall).

Ulmus hybrids

Many institutions havebeen carrying on breedingexperiments involving variouselms to produce trees resistantto Dutch elm disease. Amongthem, ‘Accolade’ has the besttrack record so far; it grows to70 ft. tall and 60 ft. wide, witharching limbs and a vase shapemuch like that of American elm.‘Danada Charm’ has a similarsize and shape but is ganglierin youth. ‘Frontier’, just 40 ft.tall and 30 ft. wide, featuresreddish purple leaves in fall.‘Homestead’, to 55 ft. tall and35 ft. wide, has a symmetricaloval to pyramidal form. ‘Patriot’forms a narrow vase shape to50 ft. tall and half as wide. ‘Triumph’grows 55 ft. tall, 50 ft.wide; it forms an upright ovalwith a strong central leader.

Ulmus parvifolia

From China, Korea, Japan. Fast growth 40 to 60 ft. tall, 50 to 70 ft. wide; often reaches 30 ft. in 5 years. Form is extremely variable, but trees are generally spreading, with long, arching, eventually weeping branchlets. On older trees, bark of trunk sheds in patches (somewhat like bark of sycamore, (Platanus), often creating beautiful mottling. Leathery dark green, 3/4-d to 2 1/2-in.-long, evenly toothed leaves. Round fruit produced in fall. Patio tree, sun screen, or (with careful pruning) street tree. Rub or cut out small branches along trunk for first few years; shorten overlong branches or strongly weeping ones to strengthen scaffolding.

Ulmus pumila

Native to Russia, northern China. Grows 50 ft. tall, 40 ft. wide. Smooth dark green leaves are 3/4 to 2 in. long. Resists Dutch elm disease and endures cold, heat, aridity, and poor soil—but has brittle wood and weak crotches and is not a desirable tree. Possibly useful in holding soil against erosion; fast growth also makes it suitable for windbreak or shelter belt. Papery, winged seeds disperse seedlings over wide area.