NSA Bethesda works hard to protect plant and animal species that are native to the area and contribute to the overall health of the ecosystem. Part of this work involves tracking, removing, and preventing the spread of invasive species. Below is a list of invasive plant species that have been found on our installation.
Garlic Mustard (Alliaria petiolata)
Garlic mustard is a biennial herb in the mustard family.
The first year of its life, the plants produce a low-growing rosette of kidney-shaped leaves.
In its second year of growth, it produces an upright stalk one to four feet tall with toothed opposite leaves small white flowers.
Seed capsules form in late spring with seeds maturing in early to mid-June.
Garlic mustard was likely introduced as a culinary herb, or medicinal plant.
It has escaped cultivation and now is reported throughout most of the US. It is shade tolerant and unpalatable to deer.
Each plant produces hundreds of seeds that remain viable for five to seven years (Swearingen et al., 2014).
Japanese Stiltgrass (Microstegium vimineum)
Japanese stiltgrass is a small grass that invades woodlands and natural areas.
It spreads by seed or vegetatively, with new roots emerging from nodes along the stem wherever it touches bare ground.
Seeds can remain viable for three years.
Leaves are approximately three inches long and have a shiny midrib (Swearingen et al., 2014).
Mile-A-Minute (Persicaria perfoliata)
Mile-A-Minute is an herbaceous, annual vine with recurved barbs on the underside of each leaf.
Leaves are triangular and have a distinctive cup-shaped structure (ocrea) around the stem at the nodes.
Fruits are deep blue berries.
Seeds are dispersed by birds or can also float on water. This species was accidentally introduced in nursery stock.
Mile-A-Minute spreads rapidly, covering other herbaceous and woody plants and killing them by blocking out sunlight (Swearingen et al., 2014).
Porcelain berry (Ampelopsis brevipedunculata)
Porcelain berry is a deciduous, woody vine in the grape family. Vines can reach fifteen to twenty feet in height, quickly climbing and smothering large trees.
It prefers open areas and moist soil. The leaves are variable in shape from heart-shaped to deeply lobed. The underside of dark green leaves are shiny with fine hairs along the veins. Tendrils grow opposite the leaves and are used to secure the plant as it grows.
Clusters of small, greenish-white flowers bloom in the summer. Small berries develop in the fall and can be a range of colors from white to green, sky blue to purple.
Originally introduces as a landscape plant, animals eat the berries and spread the seeds to other areas. There are native species of Ampelopsis and grape species that are similar in appearance (Swearingen et al., 2014).