Are Callery Pear (Pyrus calleryana) Cultivars Invasive?
NOTE: More information on this subject is available in a recent paper in BioScience. Request a PDF copy here. The Callery Pear is an ornamental tree species from China that has recently begun spreading throughout the United States with wild individuals appearing in disturbed sites. A common misconception is that certain cultivated varieties (called “cultivars”; Table 1) of this species, commonly purchased in nurseries and home improvement stores nationwide, are invasive. It is not the cultivar itself that is invasive per se, but rather the problem arises when two different cultivars cross-pollinate. Once this cross-pollination happens, fruits can be produced which are often consumed by starlings which in turn fly off to natural areas where they defecate the seeds (which then can germinate and form wild trees). Another way that wild plants can be produced is if a single Callery Pear tree is not cared for and the rootstock is allowed to sprout (this can also happen if a well-being person
