Have you ever had the sense that something is out of place, something just doesn’t belong? Years ago, on a fine summer day, I was hiking with a friend through a local nature preserve, and we were having fun quizzing each other on different plants we saw. We rounded a bend and nearly stumbled upon a small sapling quite happily growing next to the path. Silence.
“It looks like a Callery pear tree that is planted in my neighbor’s yard,” said my friend finally. We stood and pondered the obvious existence of an ornamental tree growing inexplicably in the middle of a wild area, scratching our heads and trying to figure out how it got there.
Can plants escape from our yards and gardens? And if they do, do we always know where they came from? Why do some plants seemingly sneak out of the yard but others stay put?
This guest article was written by Theresa M. Culley, evolutionary plant biologist with the University of Cincinnati.
Learning From the Past
Ornamental plants from around the world have been introduced into our area with the best of intentions – often because of their attractive flowers, leaf shape, plant form, tolerance, or desired fruit. But mistakes happen, we know that now.
Introducing purple loosestrife (Lythrum salicaria) as a garden plant with its beautiful purple spikes of blooms made sense at the time, but now we are struggling to control its wild populations spreading throughout the Midwestern U.S. We discovered that native animals, such as toads and other amphibians, are harmed by large expanses of this plant in aquatic areas.
So how can we prevent future mistakes as species continue to be introduced from areas around the world?
Genetic Sleuthing
The key is to first identify what has escaped – but this is often harder than first thought. Entire plants may escape, slowly vining their way down steep slopes or spreading across hills. Plants can also scatter to more distant areas through their seeds, carried off by birds or strong winds. Often, the offspring may not look like their mother plant, perhaps having different colored leaves or petals.
If we find a single escaped winged burning bush plant (Euonymus alatus) in the middle of the forest, how do we know where it came from? The answer is in DNA – using genetics to track the plant’s identity and even who its parents are. These genetic tools now open up a whole new way to understand how garden plants escape.
Using genetics, we now know that the wintercreeper vine (Euonymus fortunei), forming huge mats across forest floors, comes from a single ornamental cultivated variety of the same species, a “cultivar,” known as 'Coloratus.’ Wild Callery pear (Pyrus calleryana) growing in prairies and along roadsides is borne from seeds arising from cross-pollination between different popular cultivars, including ‘Bradford’, ‘Cleveland Select’, and ‘Respire’. The ‘Compactus’ cultivar of winged burning bush is escaping into forested areas nearby by birds carrying off fruits with asexually produced seeds.
We would not have made any of these discoveries without DNA. Genetics is the key to understanding what has happened in the past, so as to know what is impacting us today.
Listening to Gardens
A new effort now uses public gardens and arboreta to track plant species that escape from gardens. Named Public Gardens as Sentinels against Invasive Plants, this network shares information across North America on garden escapees, presenting information on a public dashboard. We now ask gardeners and homeowners, hiking enthusiasts, and land managers to also keep their eyes out for those out-of-place invaders of our natural areas.
Where to Report Escaped Plants
- iNaturalist – create an account to become a citizen scientist today!
- EDDMapS – another way to track and record invasive species.
About Everyday Environment
Everyday Environment is a series of blogs, podcasts, webinars, and videos exploring the intricate web of connections that tie us to the natural world.
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