Non-Native Invasive Plant Species

 

This online guide lists garden plants and weeds which are already causing significant changes to natural areas in the Mid-Atlantic. Measures for controlling each species are indicated by number, e.g., (3), in the text. For more information about non-native invasive plants, visit www.epa.gov/reg3esd1/garden/invasives/htm

There are alternatives to invasive species in our area—they are native plants. Native plants are well adapted and need little care, are attractive to birds and butterflies, and are an important part of the food web for our indigenous species. 

Most Invasive Non-Native Weeds

Garlic Mustard (Alliaria petiolata, A. officinalis) A white-flowered biennial with rough, scalloped leaves (kidney, heart, or arrow-shaped), recognizable by the smell of garlic and taste of mustard when its leaves are crushed. (The odor fades by fall.)

Control: Pull before it flowers in spring (1), removing crown and roots. Tamp down soil afterwards. Once it has flowered, cut (2), being careful not to scatter seed, then bag and burn or send to the landfill. (11) may be appropriate in some settings.

Japanese or Vietnamese Stilt Grass, Eulalia (Microstegium vimineum) Can be identified by its lime-green color and a line of silvery hairs down the middle of the 2-3" long blade. It tolerates sun or dense shade and quickly invades areas left bare or disturbed by tilling or flooding. An annual grass, it builds up a large seed bank in the soil.

Control: Easily pulled in early to mid-summer (1) - be sure to pull before it goes to seed. If seeds have formed, bag and burn or send to landfill. Mowing weekly or when it has just begun to flower may prevent it from setting seed (3). Use glyphosate (11) or herbicidal soap (less effective) on large infestations. Follow up with (5) in spring.

Mile-A-Minute Vine, Devil's Tail Tearthumb (Polygonum perfoliatum) A rapidly growing annual vine with triangular leaves, barbed stems, and turquoise berries in August which are spread by birds. It quickly covers and shades out herbaceous plants.

Control: same as for stilt grass.

Japanese Perilla, Beefsteak Plant (Perilla frutescens) Sold as a salad plant, this member of the mint family is extremely invasive by wind-borne seeds. Recognize it by the odd odor, supposedly like raw beef, when you rub it.

Control: (1); (2); (10) or (11).

Spotted Knapweed (Centaurea maculosa) A biennial with thistle-like flowers.

Canada Thustle, Bull Thistle (Cirsium arvense, C. Vulgare) Exotic thistles are far more common than native ones. If you cannot identify the species, it is probably better to remove it.

Control: Do NOT pull (1) unless the plant is young and the ground is very soft - the tap root will break off and produce several new plants. Wear sturdy gloves. (2); (6); (10) or(11).