Is It a Native Plant or Invasive? - Delaware Nature Society

Is it a native plant or invasive? How do I tell the difference?

Perhaps you’ve been hearing some rumors about something called invasive plants. It sounds like something from a horror movie “Attack of the killer plants from outer space”! Is this a real thing or just a hoax perpetuated by Martians? Sadly, invasive plants are very real and a serious threat to our natural areas. However, unless you are a plant nerd like me, you probably need some help to understand the situation.

Native plants were growing in our region before European settlement, they have co-evolved with our birds and insects to provide nutrition for raising babies, migration, and other key tasks. Non-native plants were NOT growing in our region before European settlement and have not co-evolved with our birds and insects. By definition, an invasive plant is BOTH non-native AND whose introduction has or is likely to cause economic harm, environmental harm or harm to human health (defined in the 1999 Presidential Executive Order 13112). Although this article will focus on invasive plants, other invasive species include animals (Asian Carp), insects (Spotted Lantern Fly), and even pathogens (Asian Chestnut blight).

What kind of harm can an invasive plant do?

Invasive plants can destroy or contaminate crops and cause quarantines. Economic damages to agriculture, tourism and outdoor recreation are estimated to total $137 billion per year in the United States. Changes to the plant community due to the presence of invasive plant species can increase the danger of wildfires, changes in pollen can exacerbate respiratory illnesses, and plants can serve as vectors for disease spreading illnesses such as the documented relationship between Lyme ticks and Japanese Barberry bushes. Additionally, non-natives can carry disease pathogens that infect and kill our native plants, changing our ecosystems. And studies have found that areas overrun with invasive plants produce 35 times fewer caterpillars, the most popular insect food source for the 96% of land birds that feed insects to their babies.

How do I know if I have an invasive plant in my yard?

You might have invasive plants if:

were planted by a developer or landscape contractor
were bought at a garden center, big box store, or plant swap
were given to you by another gardener who had lots of extras
are in or beside a natural area that is not managed for invasive plants

Even if you have made a point to plant only native plants, chances are good that the birds have deposited invasive plant seeds, or your neighbor’s invasives are creeping under the fence, a seed mix you used included an invasive species, or invasive seeds came in a load of mulch, topsoil or mushroom soil.

Yikes! Is it that plant taking over my butterfly garden?

It could be, but we have lots of wonderful native plants that can also be very aggressive in some situations. Many of our invasive plants might not be taking over your yard, instead they are taking over the natural area down the street.

Meet our worst invasive plants

Some of our worst invasive plants are still being sold online and in garden centers including:

Trees: Bradford Pear, Norway Maple
Shrubs: Burning Bush, Barberry, Privet
Vines: Chinese Wisteria, Autumn Clematis
Groundcovers: English Ivy, Pachysandra, Periwinkle, Wintercreeper Euonymus
Flowers & Bulbs: Common Daylily/Ditch Lily, Star of Bethlehem
Ornamental Grasses: Chinese Fountain Grass, Maiden Grass, Bamboo

Norway Maple
Bamboo
Barberry
Daylilly
Burning Bush
Fountain grass
Ivy
Maiden grass
Bradford Pear
Periwinkle
Privet
Sweet Autumn Clematis

And there are many more. In 2018, Delaware’s state biologist listed 79 plants considered invasive and another 119 that we suspect may be becoming invasive. Many of these are beautiful but, just like a laundry pod might look pretty to a toddler, pretty plants are not necessarily harmless.

Don’t despair! You can make a difference!

First, find out what you have. Post a photo to an identification app such as iNaturalist or local plant identification Facebook group, apply for certification to request a consultation from a Habitat Steward, Master Naturalist, or Master Gardener, or hire a certified Professional Landscape Designer to make you a list. All of these should be able to tell you if it is native or considered invasive in your area.

Once you have identified the invasive plants in your yard, now is a great time to start attacking them. Different plants need different control strategies, but the first step is usually to dig up as much of the plant, including roots, as you can. Check out the resources below and get your family involved.

Great native plants that replace invasives

Now you can make a plan to replant with some of our beautiful natives. Consider adding at least one of our keystone species:

Aster laeve laeve Bluebird
Birch
Blueberry
Goldenrod Solidago odora
Pine Pinus taeda
Pussy Willow Salix discolor
Red Oak Quercus rubra
Sunflower Helianthus angustifolius
Wild Cherry

These plants host 70% to 75% of our local Lepidoptera species, the Butterfly, Skipper, and Moth caterpillars that are so important for healthy baby birds.

Buy native plants at our next Native Plant Sale!

Attacking invasive plants is a great way to work out your confinement stress and aggression. Chop! Cut! Yank! Dig! Rip! Now, go get some exercise and save the planet!

Dr. Douglas Tallamy encourages everyone to engage in a new approach to conservation…one that starts in your yard, in his new book, Nature’s Best Hope. Delaware Nature Society will bring this book to life in our new on-line lecture series, “Becoming Nature’s Best Hope”. Joe Sebastiani, Ashland Nature Center Manager, and Lori Athey, Delaware Nature Society Habitat Outreach Coordinator, will engage you in local ecosystem study, native and invasive plants, good planting choices for your yard, design elements for your habitat, and lifestyle choices to become a good landlord to nature and wildlife. Join us for this 5-part series which starts April 28. Register today!