Birds easily picked up Callery pear fruits and deposited them where the tree did not exist before. This type of tree might thrive and choke out native trees.
By now most trees are finishing up their winter prep. Their leaves have turned color and dropped, and they are going dormant before freezing temperatures can damage them. But there's one type of tree -- Callery pear -- that didn't get the memo. It has only started turning color now, in mid-November. Lucky for us, because it provides one last burst of color before winter.
While Callery pear may be late to the game, it certainly doesn't wimp out. It puts on a long and dazzling color display. Its show of oranges, reds and maroons can last anywhere from 10 days to three weeks, according to Susan Wiegrefe, Morton Arboretum research associate, who has bred Callery pear trees for 11 years. "If we don't get an early frost, Callery pear can even show color in December," she said.
One drawback to Callery pear is that in central Illinois and other places it is becoming invasive. The fruits are so small, between a-quarter and three-eighths of an inch in diameter, that birds easily carry them off and spread the seeds elsewhere. Because of its adaptability, the seedlings may thrive even better than some of our native plants.
While it's not considered invasive in northern Illinois, it may be in the future, as more information becomes available. So homeowners in northern Illinois need to make an ethical choice whether to plant a Callery pear at this time, said Wiegrefe.
She and other researchers are trying to create sterile Callery pear trees that can produce flowers, but not seeds or fruit. She predicts that in the near future "we will have a Callery pear that will be adapted to our seasons and not be a threat to native plants."
The reason Callery pear waits so long to turn color is that it's programmed for a longer growing season than ours, according to Wiegrefe. It's from southern China, where, when the days get shorter, colder temperatures don't follow as quickly as they do here.
In addition to beautiful fall color, Callery pear has a "wonderful floral display in spring. It blooms before the leaves come out, so you get to see the whole tree covered in white," said Wiegrefe. In summer, glossy leaves shine. Plus, it's a pretty tough and adaptable tree. It does well in partial shade to sun, handles drought and has excellent disease resistance. "It's a great tree," said Wiegrefe. "We just need to tweak its seasonal adjustment and tone down its reproduction."
To see Callery pears in all their late fall glory, visit The Morton Arboretum, where they can be found in the China and Rose Collections. For a list of invasive trees, shrubs and vines found in northern Illinois, visit www.mortonarb.org. Under "Plant Trees," choose "Selection & Care," then "Selection Guide."
Laurie Casey is a staff writer at the Morton Arboretum in Lisle.
