Callery pear
Pyrus calleryana Decne.

SOURCE: The following information on this species is taken from the Delaware River Invasive Plant Partnership, Invasive Plant Fact Sheets at http://www.paflora.org/DRIPP.html. Modifications include additional pictures (from www.invasives.org) and resource information. Check the website links for future updates. The last update for this fact sheet is June 2003.

DESCRIPTION: Callery pear is a medium-sized deciduous tree, it grows to a height of 35-40 feet with upright branches and a very dense, symmetrical crown.

Stem - Callery pear trees have scaly gray-brown bark and branches with numerous short lateral twigs. Twigs ending in thorns are typical of the species, but the Bradford cultivar is thornless.
Leaves - The leaves are simple, 2-3 inches long, broadest near the rounded base and tapering to the tip. They are light to dark green and glossy with a wavy edge. The leaves remain green late into the fall and finally turn a deep red color before falling.
Flowers - Callery pear is one of the earliest trees to flower in the spring, well before the leaves appear. The flowers are white, about ¾ inch in diameter, with five white petals.
Fruit and seed - Callery pear fruits are small, ¼-½ inch in diameter, and hard and brown when ripe; each fruit contains 2-4 shiny black seeds. Birds and small mammals eat the fruits.

Photos: (clockwise from top left): Britt Slattery, U.S. Fish and Wildlife Service, www.forestryimages.org; (2) Chuck Bargeron, The University of Georgia, www.forestryimages.org; from Fact Sheet

DISTRIBUTION AND HABITAT: Callery pear is native to China; in 1918 seed was brought to the United States for potential use as rootstock for cultivated pears. Of the initial batch of 100 pounds of seed that was planted at the Plant Introduction Station at Glen Dale, Maryland , one vigorous, non-spiny seedling was selected and named "Bradford". The 'Bradford' callery pear proved to be an attractive landscape specimen with a neat growth form, attractive flowers and foliage, and no pests. Furthermore Bradford was not self-pollinating and thus no fruit or seeds were produced. The landscape industry popularized it and before long it was being planted in urban and suburban settings from parking lots and streets to home landscapes. In 1982 the National Landscape Association voted 'Bradford' callery pear the second most popular tree in America.

However, with time other callery pear cultivars were developed and introduced into the nursery trade. With several cultivars in circulation, cross-pollination could take place and the trees began to produce fruits and seeds.

The spread of callery pear along roadsides, rights-of-way, and in successional old fields was first noticed in southern Maryland and around Washington, DC. In Pennsylvania naturalized populations are known in Bucks and Montgomery Counties. Naturalized populations generally exhibit characteristics of the species including wide-spreading branches and thorniness. Fruit size may vary from ¼ inch to nearly 1 inch in diameter.

EFFECTS OF INVASION: Naturalized callery pear competes with native early successional trees in old fields and hedgerows.

REPRODUCTION AND METHODS OF DISPERSAL: The spread of callery pear is by seed, apparently dispersed by birds, and perhaps also small mammals, that consume the small hard fruits and excrete the seeds when they defecate.

NATIVE ALTERNATIVES FOR LANDSCAPE USE: Native small, flowering trees such as shadbush or juneberry (Amelanchier arborea, Amelanchier laevis), alternate-leaved dogwood (Cornus alternifolia), blackhaw (Viburnum prunifolium), or cockspur hawthorn (Crataegus crus-galli) are suitable for landscape use.

AUTHORS: Ann F. Rhoads and Timothy A. Block, Morris Arboretum, University of Pennsylvania.

For more information on callery pear, please contact:
Delaware River Invasive Plant Partnership, http://www.paflora.org/DRIPP.html.
Mid-Atlantic Exotic Pest Plant Council, Inc., http://www.ma-eppc.org
National Invasive Species Information Center, http://www.invasivespeciesinfo.gov
Plant Invaders of Mid-Atlantic Natural Areas, http://www.nps.gov/plants/alien/pubs/midatlantic/
The Bugwood Network, MA-EPPC Plant List, http://www.invasive.org/maweeds.cfm
USDA Forest Service, Northeastern Area, http://www.na.fs.fed.us/fhp/invasive_plants/weeds/.
USDA-NRCS PLANTS Database, http://plants.usda.gov

REFERENCES:
Rhoads, A. F. and T. A. Block. 2000. The Plants of Pennsylvania, An Illustrated Manual. University of Pennsylvania Press, Philadelphia.

Management and Control Information

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