Japanese Stilt Grass
Microstegium vimineum

How did it get here?

Japanese Stilt Grass Range MapFirst identified in Knoxville, Tennessee in 1919, this grass may have been introduced accidentally through its use as a packing material for Chinese porcelain. Its native range is Japan, Korea, China, Malaysia, and India. Japanese stilt grass was found in western North Carolina in 1933.

How to spot

Japanese Stilt Grass closeup of leaves - invasives.orgMicrostegium vimineum grows in a sprawling pattern and may form colonies to 3 feet in height. It has a branched stalk with alternate leaves that are thin, pale green, lance-shaped, and about 3 inches long. The leaves have a silvery strip of reflective hairs in the center of the upper surface. Delicate spikes of flowers appear near the tips of the stalks in late summer and early fall.

Habitat characteristics

  • Moderate to dense shade.
  • Moist, nitrogen-rich soils with acidic to neutral pH.
  • Naturally or artificially disturbed sites such as roadsides, ditches, woodland borders, floodplains, and streamsides.
  • Selectively colonizes bare ground not occupied by other plants.

Life cycle

Japanese stilt grass is an annual that reproduces from seed. The grass grows in colonies, rooting from the nodes and sometimes forming dense stands of the same plant. Each plant produces as many as 1,000 seeds that remain viable in the soil for at least five years. Seeds are dispersed naturally by wind and water (streams and ditches) and are transported by humans in hay and soil.

Look-alikes and how to distinguish

  • Cutgrass (Leersia virginica)—longer leaves.
  • Knotweed (Polygonum persicaria)—pale to dark-pink calyx and glossy, brown nutlets.

Why is this plant a problem?

Japanese Stilt Grass infestation - invasives.orgAlthough it is generally slow to colonize undisturbed areas, Japanese stilt grass can rapidly fill disturbed areas such as streamsides scoured by flooding and sewer line rights-of-way that are mown annually. The dense stands that it forms can crowd out native vegetation in just a few years. Once these stands are established, the natural soil conditions such as pH and organic composition begin to change, potentially preventing the re-establishment of the original native species. Deer do not eat Japanese stilt grass, giving the plant an advantage in heavily grazed locations.

Management approaches

  • Avoid disturbing vegetation and soil in areas free of this grass.
  • Control new infestations early to prevent establishment. Seed will persist in soil for many years.
  • Pull by hand (in small areas) or use a mower or powered weeder (in large areas) when plant is in peak bloom but before it produces seeds. This occurs in late summer in the Southeast. If plants are pulled too early, additional seeds in soil will have time to germinate and replace the stand. Dislodge shallow roots completely, as plants break off easily.

Other resources
WEB

Plant Conservation Alliance, Alien Plant Working Group

Southern Appalachian Man and the Biosphere

Southeast Exotic Pest Plant Council, Invasive Plant Manual

Element Stewardship Abstract for Microstegium vimineum

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