My Big Beef with Barberry

I like to compare learning to identify invasive plants to learning a new word. When you learn a new word, you suddenly hear it all the time. Similarly, once you learn what certain invasive species look like, you find one around every corner. Learn a species a month, with our invasive species blog series, starting with Japanese barberry!

My daily walks lead me down a street just like any other – a street lined with homes, yards, and public space. Some segments have native flowers, ground cover, and sedges, but some are taken over by lines of invasive shrubs like Japanese barberry.

Japanese Barberry: The Villain of Invasives!

Rows of Japanese Barberry line segments of many residential streets, including mine.

Japanese barberry (Berberis thunbergii) is a common landscaping choice, despite its invasive status and pesky thorns. It’s hardy, easily maintained, and takes on an attractive reddish, purplish hue. I, however, have a contentious relationship with the shrub. My major beef with the plant is its association with Lyme disease.

Due to its density, Japanese barberry is warmer and more humid than other shrubs, creating an optimal environment for ticks to thrive and reproduce. White-footed mice, which are common carriers of the bacteria that causes Lyme disease, often traverse the dense, thorny branches for protection. One infected mouse can transfer the bacteria to multiple ticks – ticks that can pass it on to you!

Dr. Scott Williams, lead researcher on Japanese barberry for the Connecticut Agricultural Experiment Station (CAES), found an acre of forest containing Japanese barberry averages a Lyme disease-carrying tick population 12 times higher than an acre with no barberry.

Japanese barberry’s dense clusters of oval-shaped leaves make an ideal environment for Lyme disease-carrying mice.

Although the shrub was added to the Pennsylvania noxious weed list in 2021, and is no longer allowed be distributed, cultivated, or propagated within the Commonwealth, it is still present in landscaping, if planted before the ban. It’s important to know how to identify the shrub, whether you’re taking a walk in the city, or hiking in a wooded area. Keep an eye out for its dense, irregular clusters of oval leaves, red, oblong fruit, and generally short, wide stature. Learn more about how to identify and control Japanese barberry here, and its correlation with Lyme disease here.

Nobody’s Neighborhood is Immune to Invasive Species

Unfortunately, invasive plants are clever, and can carve out niches where some native plants may not succeed. Because of this, they can outcompete native plants, reducing biodiversity and, therefore, habitat for native animals.

Periwinkle (Vinca minor), another common landscaping choice amongst homeowners, is also prevalent in my neighborhood. It thrives in both open and shady areas, and can easily escape from its landscaped area. Like many other invasive plants, it grows vigorously and forms dense mats that can displace native plants. Walking down my street, I spot additional invasive species like tree of heaven (Ailanthus altissima), and English ivy (Hedera helix) at a fast-paced glance. Who knows what else lurks upon a closer look!

Periwinkle effortlessly creates monocultures and shades out anything that might grow below it.

At no fault of homeowners, local officials, or other entities, every neighborhood is likely to have some invasive plants sprouting up. Luckily, there are plenty of resources to find native plant nurseries near you. You can also decide which plant is right for your space with the Alliance’s Native Plant Center.

If you’re ever unsure if a plant is invasive, check out invasive.org and Seek by iNaturalist. Invasive.org is a great resource for learning almost everything about an invasive you may come across, or just learning the basics of what invasive species are! Seek is a convenient smartphone app that can identify plants and animals on the spot, and I use it regularly.

Part of the reason invasive plants are so prominent is because people simply don’t know much about them! We can all talk to our friends, family, and neighbors to spread the word about the negative effects of invasive species. The more we all know, the more we can do to create healthier neighborhoods, ecosystems, and communities. Do you want to learn more about invasive species? Stay tuned for more invasive species blogs this season!