|I don't have to go far to find an example like this|
Some folks might kindly think that someone planted the pear tree on the edge of the woods or in that vacant lot. Probably not. Roadsides and waste lots are showing more and more signs of invasion. I pull them out of my yard on a regular basis because of trees in the neighborhood. I see them growing on the edge of my neighbors' yards, unrecognized for the invader that they are.
How did this happen? Ornamental pears are native to southeast Asia; as the common name implies, the fruits are small and not considered edible by most humans (although they probably could be eaten). The cultivar 'Bradford' was created as a self-sterile ornamental tree that would not create even those small fruits.
Then 'Bradford' was discovered to have weak branching, causing it to split in storms (and sometimes even without a storm). Nurserymen developed new cultivars like 'Aristocrat' and 'Cleveland Select.' Unfortunately, cross-pollination was now possible between the cultivars, allowing ALL the trees to produce small but viable fruits. Trees that were previously sterile would now produce fruit if a different cultivar was within range.
|Fruit on Pyrus calleryana|
Wildlife such as birds and squirrels help spread these fruits, allowing new plants to grow in wild and un-managed areas. The vigor of these seedlings allows them to grow fast, out-competing other plants and creating dense thickets over time. The seedlings are sometimes thorny, a characteristic of the original species that was bred out of the cultivars being sold.
I applaud communities like Columbia, Missouri that are helping to make its citizens aware of what is happening. Too often people just let "nature take its course." I encourage you to look out for strange plants popping up in your yard. Pear seedlings usually have a notch in the leaf and turn bright red in the fall. Please pull up and discard any that you find. There are far better things to cultivate.
|Notice the notch in the leaf on the lower left side|
For more pictures to help you identify this weedy tree, please see my earlier post on this.