Callery Pear AKA Pyrus calleryana
This spring, for the first time, I noticed a small attractive tree with showy white flowers growing near the border of a state-owned field across from our house. It being something new to me, I snapped a picture of it and asked my smart phone for an ID. The phone readily complied suggesting the tree was a wild Callery pear tree. In searching for more information, I found first of all that The Id. provided by my phone was correct, and secondly that these trees are yet another invasive plant.
Here is a tad of history about how they arrived on our shores and how they became invasive should you be interested. The trees were brought here from China, along with many other plants, during the early 1900's. It is during this time period that ranching in the Pacific Northwest began to transition to farming. Many trees and plants likely to survive in that climate were transported from not only various parts of the United States, but from other countries as well. Great emphasis was placed on exploring China for potential imports as the climate in parts of China was similar to that of the Pacific Northwest. It was believed plants from those areas in China would likely survive and thrive here. Previously, in the Pacific Northwest, orchards had been planted with numerous French pear trees. Sadly, multitudes of these trees were succumbing to a disease called fire blight. A diseased tree would exhibit branches and leaves that appeared shriveled, looking exactly as though they had been through a fire. Just in the nick of time plant explorers in China discovered the extremely hardy Callery pear tree. The trees were so self-preserving they even had spiny thornlike growths along their branches which deterred wildlife from grazing on them. Grafting the French pear trees to Callery pear rootstalk seemed like the perfect solution for the survival of the diseased French pear trees. Callery pear seeds were imported from China by the thousands and from them thousands of trees were successfully grown, and varieties of the less hardy pear trees were then grafted to them. Problem solved? Well yes and no. The fire blight issue was resolved, but let's fast forward to the year 1952. This is when John Creech from the USDA happened to observe one of the older remaining Callery pear trees that was being grown as potential rootstalk. The glossy leaves, the globular form, and tree's showy bloom struck him as very appealing. Additionally, this particular Callery pear tree did not exhibit the usual sharp thorn like spurs on its branches. Seeing its potential as a landscape tree, he started several scions, essentially clones, from cuttings of the tree's branches and named the resultant trees Bradford pear trees. The USDA continued to grow more and more of these clones. During the housing boom in the 1960's, the Bradford pear trees were heavily marketed. After the successful marketing campaign, the trees were found just about everywhere. Bradford pear trees are not self-fertile. Even if you plant two Bradford pear trees near each other they are essentially sterile. Therefore, Bradford pear trees could safely be grown as ornamental trees without danger of overpopulating the environment.
By the 1980's, as the trees matured, problems with branch breakage, sometimes resulting in total tree breakage, began to occur. Since the tree was such a popular ornamental, alternative cultivars were developed, each, on its own, essentially sterile. This is where the invasive outlaw problem began. Unfortunately, the several different cultivars of Callery pear trees developed and marketed in the 1980's, though sterile individually, were able to cross pollinate with each other. They could also cross pollinate with the Bradford pear. In addition, the new cultivars were capable of cross pollination with cultivated orchard varieties of fruit bearing pear trees. The seeds and resultant trees from cross pollinated ornamental pear trees reverted to the original imported Callery pear trees with all of their wild traits, including the trait of those tough sharp 4" thorn like spines! The wild Callery pear trees are no longer sterile. They bear numerous small round fruit each containing several seeds within. As some of that fruit is consumed by birds, the seeds pass through their digestive tracts and are scattered through the landscape while the birds are on their travels. Eventually these seeds germinate creating a new colony of wild thorny pear trees also capable of reproducing. Any fruit not consumed drops close to the original tree and germinates in place beginning the creation of a thicket of these invasive trees. As if that is not enough, the trees send out lateral roots occasionally sending up shoots forming yet more trees. Dense thickets of these thorny trees can prevent wildlife from passing through and birds from nesting. Woodland areas infested with these invasive trees become unpassable for human recreational activities as well.
So, how exactly did that tree get in the field across from our house? I believe the Bosc and Bartlett pear trees growing in our orchard somehow became cross pollinated with a Callery pear tree, either a wild one or somebody's ornamental. Several years ago, a gang of criminal squirrels harvested our entire crop of perfectly ripened pears for themselves. They are the likely culprits responsible for planting the Callery pear tree I observed in that field, and I fear there will be more!
You can readily identify a wild Callery pear tree. Its leaves look glossy and similar in form to that of a regular pear tree. The wild Callery pear has the numerous sharp woody thorns that grow along its branches. Another identifying characteristic of either wild or cultivated Callery and Bradford pear trees is the abundant showy white flowers which are said to smell like rotting fish or urine. The odor attracts flies which are the trees primary pollinators. I have to say I did not notice that odor when I photographed the wild pear in the field for smart phone identification, but I did not get all that close to the tree either. Callery pears are considered invasive in many states including Connecticut. According the UCONN invasive plant list, Callery pear cultivars will be banned for sale in Connecticut beginning in 2027. Beware! as of 2025 Bradford pear and Callery pear cultivars are still being sold in Connecticut!! There are many attractive native alternatives that bear flowers that don't smell like urine or rotting fish! Select one of those instead.
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