Ted Bodner

Japanese Stilt Grass
Microstegium vimineum

Origin: Japan, Korea, China, Malaysia and India

Background
Japanese stilt grass was first introduced into the United States in Tennessee around 1919 and likely escaped as a result of its use as a packing material for porcelain.

Distribution and Ecological Threat
Japanese stilt grass is currently established in 16 eastern states, from New York to Florida. It occurs on stream banks, river bluffs, floodplains, emergent and forested wetlands, moist woodlands, early successional fields, uplands, thickets, roadside ditches, gas and power-line corridors, lawns and gardens. Japanese stilt grass threatens native understory vegetation in full sun to deep shade. Stilt grass readily invades disturbed shaded areas, like floodplains that are prone to natural scouring, and areas subject to mowing, tilling and other soil-disturbing activities including white-tailed deer traffic. It spreads opportunistically following disturbance to form dense patches, displacing native wetland and forest vegetation as the patch expands. Japanese stilt grass appears to be associated with moist, acidic to neutral soils that are high in nitrogen.

James H. Miller

Description and Biology

• Plant: an annual in the grass family (Poaceae) resembling a small, delicate bamboo; mature plants are 2 to 3 feet in height.
• Leaves: pale green, lance-shaped, asymmetrical, about 3 inches in length, with a shiny midrib.
• Flowers, fruits and seeds: delicate spikes of flowers emerge from slender tips in late summer and early fall. Fruits are produced shortly after flowering and then the entire plant dies.
• Spreads: vegetatively by rooting at joints along the stem (a new plant can emerge from each node) and by seed. A single plant can produce 100 to 1,000 seeds that remain viable in the soil for at least three years, ensuring its persistence. Stilt grass seed germinates readily following soil disturbance. Although dispersal is not fully understood, seeds are probably transported by movement of water (e.g. surface runoff, streams, and floodwaters), soil, plants and on the feet of other animals including people.
• Look-alikes: Virginia cutgrass (Leersia virginica), hairy jointgrass or small carpetgrass (Arthraxon hispidus), and possibly other delicate grasses and wildflowers like Pennsylvania knotweed (Polygonum persicaria).

Prevention and Control
Because it is similar in appearance to several native grasses, it is important to know how to recognize and differentiate stilt grass from look-alikes. The shiny midrib and asymmetrical leaves help to distinguish stilt grass. Early attention to new infestations should be a priority. Because it is shallow-rooted, stilt grass may be pulled by hand at any time. Flowering plants can be cut back using a mower or weed whip prior to seed production. For extensive infestations, contact and systemic herbicides may be more practical and effective.

Native Alternatives
Following disturbance to an area susceptible to stiltgrass, stabilize with native vegetation suitable to site conditions. Refer to References.

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Publication by USFWS BayScapes Conservation Landscaping Program
http://www.nps.gov/plants/alien/pubs/midatlantic/mivi.htm
Last updated: 7 October 2004