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1 December 2007 The Beginning of a New Invasive Plant: A History of the Ornamental Callery Pear in the United States
THERESA M. CULLEY, NICOLE A. HARDIMAN
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Abstract

The Callery pear (Pyrus calleryana Dcne. [Rosales: Rosaceae]), an ornamental tree from China, has begun appearing in disturbed areas throughout the United States. To understand the relatively recent spread of this species into natural areas, we review its horticultural history, the traits promoting its invasiveness, and its current invasive status. Cultivated varieties (cultivars) of this species sold in the United States originate from different areas in China and represent genotypes that have been planted in high densities in residential and commercial areas in the introduced range. The species cannot self-pollinate because of a self-incompatibility system, but recent fruit set is due to crossing between different cultivars or between the scion and rootstock of cultivated individuals. Consequently, individual cultivars themselves are not invasive, but the combination of cultivars within an area creates a situation in which invasive plants can be produced. Because of the established nature of this species in urban areas, the spread of wild P. calleryana will most likely continue, especially as new cultivars continue to be introduced into the mixture of cultivars already present.

THERESA M. CULLEY and NICOLE A. HARDIMAN "The Beginning of a New Invasive Plant: A History of the Ornamental Callery Pear in the United States," BioScience 57(11), 956-964, (1 December 2007). https://doi.org/10.1641/B571108
Published: 1 December 2007
JOURNAL ARTICLE
9 PAGES

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