On the Trail: Pear trees have left a mixed legacy

The most recognizable trees right now are, without a doubt, the ornamental pear trees. Full of white blossoms and smelling faintly of dead fish, once you start seeing (and smelling) these trees, you realize that they are everywhere, including lots of places they were never intended to be.

Introduced to the United States in the early 1900s, by the 1960s, the Callery Pear (Pyrus calleryana), which is native to Vietnam and China, was being heavily promoted as a new ornamental and planted aggressively in yards and urban landscapes. As noted, the trees produce an early burst of white blooms, they are fast growing, and they can have nice fall color.

What makes this story interesting and unfortunate is that while the individual varieties of ornamental pear, like the Bradford variety, are generally unable to produce fertile seeds when self-pollinated, if different varieties are grown in close proximity, they can cross-pollinate and produce fertile seeds that are then spread by birds across the landscape.

The resulting “wild trees” then produce more viable seed, furthering the expansion and dispersal of the species. As a result, Callery pears sometimes form extensive, homogeneous stands in old fields and on regenerating lands that have the potential to become future forests. Callery pear trees can also be found invading established natural habitats.

As with most nonnative species, the ornamental pears have little to no wildlife value, and they can choke out native trees. Callery pears are like food deserts for birds, because there are no native caterpillars that feed on the foliage. And doghair stands of Callery pears can create a “dead zone” beneath a dense canopy.

The conservation community’s response to the Callery pear invasion has been aggressive. Ohio and South Carolina have banned the sale of Callery pears in their states ,and others are likely to follow. And this spring a local business specializing in invasive plant species control is offering a chance to win free removal of up to 10 trees if you like and follow their Facebook page!

Short of removing them, the ornamental pears are relatively short-lived trees, so if you’ve got one in your yard, and you are waiting for it to die of natural causes, you might not have to wait too long.

The really good news is that if you are looking for native alternatives to Bradford pears to landscape with, there are several native species that provide beautiful spring blooms including elderberry, downy serviceberry, vernal witchhazel, black chokeberry, American plum, flowering dogwood and eastern redbud.

Finally, there is a Keep Carbondale Beautiful tree and shrub sale this weekend, and many of those native species will be available for purchase. The tree sale is Saturday, March 23 from 8:30 a.m. to 2 p.m. at the Town Square Pavilion in downtown Carbondale. Trees will sell for $40 and shrubs for $35, and all proceeds from the sale will go to support the work of Keep Carbondale Beautiful.

• Michael Eric Baltz writes about the changing world from his home in Carbondale.