Claudia Thompson-Deahl is a long time mountain resident, and an awesome plant knowledge base. She’s volunteered this article on invasive species on the mountain
I have lived in Bull Run Mountain Estates since 1986 and have lived in Western Prince William County since the late 70’s. I moved to Bull Run because of the feel of the community-laid back, different home styles, it’s a great place to raise kids, and the nature on the mountain. I am a frequent walker just for exercise on our mountain roads. Lately I have noticed an increase in invasive plants and wanted to share with my friends and neighbors what I know about this plant in particular. There are 2 invasive wisterias, Chinese Wisteria Wisteria sinensis , and Japanese Wisteria Wisteria floribunda. They are in the Pea family and are native to China and Japan. We do have a Native American wisteria that has similar flowers but does not act as aggressively as the Chinese and Japanese species. It’s important to ask for the native species when purchasing plants to get more native species into the horticulture trade.
Invasive Wisterias have been increasing at an alarming rate on our mountain. You are probably already know about invasive plants, they are plants that are non-native, aggressively reproduce and negatively affect the ecology of the area. They climb and pull down even well established trees and create a solid monoculture of wisteria. They are overtake our wonderful mountain laurel, chestnut oaks and other native plants by strangling or shading even smothering our native ground covers. Both wisterias will grow in full sun or shade.
Both the Chinese and Japanese Wisterias have 4-6 inch long velvety seed pods. Stems of the exotic wisterias can grow to an astonishing 15 inches in diameter in older plants! They have compound leaves as you can see in the photo. Chinese wisteria has 7-13 leaflets and the Japanese species has 13-19. Infestations are commonly found along forest and road edges, roadsides, ditches, and rights-of-way. Although the blue-violet flowers are showy, it’s simply not worth the destruction they cause to our woodlots.