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Landscaper’s darling hybridizes into an environmental nuisance

Variation underlies the Callery pear tree’s transformation

As in other tales of nice kids gone wrong, the Callery pear tree’s troubles can be traced to a gang of new pals, a new genetic analysis suggests.

Imported from China, the Callery pear won U.S. hearts and yards coast to coast for its early spring clouds of white blossoms. The first ornamental variety of the species, named Bradford, went on sale in the early 1960s. It didn’t form fruit, so there would be no squishies on sidewalks or seeds escaping to sprout in native areas. Bradford’s success inspired the introduction of other named varieties.

Now many Callery pear varieties in the eastern United States bear bumper crops of hard, marble-sized fruits, says Theresa Culley of the University of Cincinnati. Animals distribute the seeds, and they sprout into dense thickets, sometimes with thorns, that can crowd out other plants.

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