U.S. National Arboretum Plant Introduction

Floral and Nursery Plants Research Unit

U.S. National Arboretum, U.S. Department of Agriculture, Agricultural Research Service, 3501 New York Ave., N.E., Washington, DC 20002

The U.S. National Arboretum presents Ulmus wilsoniana 'Prospector', an elm

of Asian origin with proven pest and Dutch elm disease resistance. 'Prospector'

offers the vase shape, dense crown, and large green leaves of its American cousin but in

a smaller package. It is a great choice for spaces that need an American elm but aren’t

quite large enough. Try 'Prospector' as a street tree, under power lines, in municipal

sites or parks, and, of course, at home.

Ulmus wilsoniana 'Prospector'

'Prospector', left; American elm, right
U.S. National Arboretum Plant Introduction

Floral and Nursery Plants Research Unit

U.S. National Arboretum: www.ars-grin.gov/na/

Botanical Name:

Family:

Hardiness:

Development:

Significance:

Description:

Culture:

Propagation:

Landscape Use:

Availability:

'Prospector' Wilson Elm

November 1999

The U.S. Department of Agriculture is an Equal Opportunity Employer.

Ulmus wilsoniana Schneid. 'Prospector'

(NA 55398; PI 536050)

Ulmaceae

U.S.D.A. Zones (4)5–7

'Prospector' elm was initially selected by A.M. Townsend and L.R.

Schrieber in 1975 from a 1965 planting of U. wilsoniana seedlings in

Delaware, Ohio. Over the next 15 years, this plant demonstrated a

high level of resistance in both laboratory and field trials to the

fungus that causes Dutch elm disease (DED) and to elm leaf beetle.

'Prospector' was named and released in May, 1990.

The Dutch elm disease epidemic of the 20th century sparked a great

interest in Asian elm species as potential replacements for the

American elm because of their inherent tolerance or resistance to

DED. The Chinese species, U. wilsoniana, which resembles a small

American elm in form and leaf, was an excellent prospect for evaluation in DED trials. 'Prospector' is the first cultivar of U. wilsoniana

selected and released in the United States. It has consistently

exhibited superior tolerance to DED and elm leaf beetle.

Height and Width: Approximately 50 feet tall, 25 foot crown spread

at maturity. Smaller than American elm.

Growth Rate: Moderately fast; 23 feet tall and 21 foot crown spread

at 10 years under normal nursery conditions. Vigorous.

Habit: Deciduous tree with vase-shaped crown, similar to American

elm, but pendulous at much lower height; dense canopy.

Foliage: Leaves 4 1/2 inches long, 3 1/3 inches wide, obovate. New

leaves emerge orange red and mature to green; good yellow fall color.

Bark: Light grey.

Flowers: Very early spring; inconspicuous; not ornamental.

Fruit: Small; samaras emerge green, dry to brown; not weedy.

Grows best in well-drained soil. Tolerates somewhat adverse sites.

Successfully grown in Maryland, California, Ohio, Oklahoma, Oregon,

Tennessee, Virginia. Requires regular pruning to maintain form due

to vigorous early growth.

Roots easily from softwood cuttings under mist, 3000–8000 ppm IBA,

in 3–4 weeks.

Locations requiring small to intermediate-sized shade tree: Parks,

lawns, streets, or highways, under power lines.

Limited availability from wholesale nurseries.