Japanese stiltgrass, or Nepalese browntop, was introduced into the United States in Tennessee around 1919 and likely escaped as a result of its use as a packing material for porcelain. Stiltgrass threatens native understory vegetation in full sun to deep shade. It 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. It occurs on stream banks, river bluffs, floodplains, emergent and forested wetlands, moist woodlands, early successional fields, uplands, thickets, roadside ditches, and gas and power-line corridors. It can be found in full sun to deep shaded forest conditions and is associated with moist, rich soils that are acidic, neutral or basic and high in nitrogen.
Japanese stiltgrass is an annual grass with a sprawling habit. It germinates in spring and grows slowly through the summer months, ultimately reaching heights of 2 to 3½ ft. The leaves are pale green, lance-shaped, asymmetrical, 1 to 3 in. long, and have a distinctive shiny midrib. Slender stalks of tiny flowers are produced in late summer (August through September-early October) and dry fruits called achenes are produced soon afterwards.
Stiltgrass is currently established in 16 eastern states, from New York to Florida.
Because it is shallow-rooted, stiltgrass may be pulled by hand at any time. If flowering, cut plants back using a mower, weed whip or other device to prevent seed production. For extensive infestations, herbicides are the most practical and effective method currently.
What Can You Do?
Because it is similar in appearance to several native grasses, it is important to know how to recognize and differentiate stiltgrass from look-alikes. Look for asymmetrical leaves with a shiny midrib and the stilt-like growth form. Attention to new infestations should be a priority.