'Princeton' Elm

Princeton Elm (Ulmus americana 'Princeton')

'Princeton' is a pure American elm cultivar (Ulmus americana) originally selected in 1922 for landscape form and later identified as a Dutch Elm Disease survivor. It is one of the few pre-DED selections still in commercial production and has been widely used in restoration plantings, including the elms on the National Mall in Washington, D.C.

Origin

'Princeton' was introduced in 1922 by Princeton Nurseries (New Jersey), selected by William Flemer for its classic vase-shaped form and vigorous growth. The cultivar predates the 1930 arrival of Ophiostoma ulmi in North America and survived early DED waves at numerous plantings.

Mature 'Princeton' specimens were re-evaluated for DED tolerance in USDA inoculation trials in the 1990s. The cultivar demonstrated sufficient resistance to be reissued for commercial landscape use, though its resistance is generally rated below that of newer USDA releases such as 'Valley Forge' and 'New Harmony'.

Identification

Form: Classic American elm vase shape with a strong central leader splitting into three to five ascending scaffold branches

Mature size: 60–70 feet tall, 40–60 foot crown spread

Leaves: Standard Ulmus americana foliage — 3–5 inch oval, double-serrated, asymmetric base, dark green

Bark: Light gray, deeply furrowed at maturity

Growth rate: Fast (2–3 feet per year when established)

Hardiness and adaptability

USDA hardiness zones: 4–9

Site preferences: Moist, well-drained soils; tolerant of urban conditions, compaction, and a wide pH range

Stress tolerance: Moderate drought tolerance once established; relatively salt-tolerant

Dutch Elm Disease resistance

'Princeton' shows moderate to good DED resistance. In USDA inoculation trials it demonstrated meaningful tolerance but not the near-immunity reported for 'Valley Forge' or 'New Harmony' (Townsend et al. 2005). Field survival rates in moderate-pressure environments are typically reported in the 70–85% range.

The National Elm Trial (Griffin et al. 2017), a 10-year multi-site evaluation across 16 US locations, ranked 'Princeton' as a serviceable urban cultivar with disease losses lower than non-resistant American elm seedlings but higher than the top-rated USDA hybrids.

Landscape uses

Street trees in regions where the classic American elm form is valued

Large-scale restoration plantings, including the National Mall replantings begun in 2005

Park and estate plantings emphasizing historic American elm aesthetics

Most successful when planted as part of a mixed cultivar palette to reduce monoculture vulnerability

Limitations

Resistance is not at the level of the newer USDA hybrids; trees can still succumb under heavy disease pressure

Susceptible to elm yellows, a phytoplasma disease distinct from DED (see Elm Yellows vs Dutch Elm Disease)

Variable form when young; canopy structure develops over decades

Like all American elms, requires careful early pruning to establish a strong scaffold

Similar cultivars

'Valley Forge' — also pure American elm, higher DED resistance

'New Harmony' — USDA companion release to Valley Forge

'Jefferson' — hexaploid American elm with high resistance

Related pages

What Cultivars Are Resistant to Dutch Elm Disease?

Disease-Resistant Varieties Guide

American Elm (Ulmus americana)

References

Townsend, A. M., Bentz, S. E., & Douglass, L. W. (2005). "Evaluation of 19 American elm clones for tolerance to Dutch elm disease." Journal of Environmental Horticulture, 23(1), 21–24.

Griffin, J. J., Jacobi, W. R., McPherson, E. G., et al. (2017). "Ten-year performance of the United States National Elm Trial." Arboriculture & Urban Forestry, 43(3), 107–120.

Santamour, F. S., & Bentz, S. E. (1995). "Updated checklist of elm (Ulmus) cultivars for use in North America." Journal of Arboriculture, 21(3), 122–131.