Plants are ingenious at spreading by seed. Seeds are designed to be carried by the wind, entice birds to eat them and disperse them with a little poop, flow along with run-off water, and explode with a pop to gain some space of their own. One seed can lead to so many more. One plant of narrowleaf bittercress can produce 5,500 seeds! No wonder farmers and gardeners say, “One year of seed, seven years of weeds.”

When you prevent weeds from growing on your property and going to seed, you prevent them from spreading to other places—like the beautiful state parks and forests of Pennsylvania. This practice is particularly important for invasive plants.

To start, identify the unwanted plant. Today, with cell phones and apps like iNaturalist, Seek, and Picture this, plant identification is easier than ever. Some unwanted plants may be considered invasive to your area. By one definition, invasive species are not indigenous to the region and cause harm to the environment, economy, or human health.  Most invasive species easily adapt to a new environment, have high rates of reproduction, and lack predators. Besides plants, invasive species include viruses, bacteria, insects, and other animals. Examples of these are West Nile virus, Woolly Hemlock adelgid, Spotted Lanternfly, and Jumping earthworms.

It helps to become familiar with the common invasive plants of your area. Where I live in New York, these include Oriental bittersweet, Japanese barberry, winged euonymus, Japanese stilt grass, garlic mustard, mugwort, ground ivy, sheep sorrel, phragmites, Japanese honeysuckle bush and vine, wine berry, multiflora rose, Russian and autumn olive, fig buttercup, Bishop’s weed, Japanese knotweed,  mile-a-minute, porcelain berry, Chinese and Japanese wisteria, swallowwort,  Canadian thistle, privet, photinia, Linden viburnum, Norway maple, Ailanthus trees, black Locust trees, Japanese aralia tree, glossy buckthorn.  Whew! And there are more coming.

Because invasive species will be re-introduced by the wind, water or birds, it behooves us to monitor our properties regularly to prevent their spread. In another blog, I’ll write about management strategies.

Helpful resources are:

• Invasive Plants in Pennsylvania, PA Department of Conservation & Natural Resources
• Plant Invaders of Mid-Atlantic Natural Areas
• https://www.invasive.org/eastern/Midatlantic/
• Woody invasive species https://woodyinvasives.org/woody-invasive-species/
• Mistaken Identity? Invasive Plants and their Native Look-Alikes
• http://www.nybg.org/files/scientists/rnaczi/Mistaken_Identity_Final.pdf

 – Carolyn Reppert Sears, Ph.D.

Dr. Sears lives in NY but has strong familial ties to PA. Retired from a career teaching science, she is co-director of The Invasives Project-Pound Ridge (NY), a volunteer effort to protect the natural beauty of her small town, preserve wildlife habitat, encourage the use of native plant species, and limit the spread of invasive species.

Feature photo: An invasive rogues gallery: giant hogweed, garlic mustard, Japanese honeysuckle, buckthorn