Nepalese Browntop, Japanese Stiltgrass (Microstegium vimineum)
Miller, J.H., E.B, Chambliss, N.J. Loewenstein. 2010. A Field Guide for the Identification of Invasive Plants in Southern Forests. General Technical Report SRS-119. Asheville, NC. United States Department of Agriculture, Forest Service. 126 p.
Sprawling, annual grass, 0.5 to 3 feet (15 to 90 cm) in height. Flat, short leaf blades with offcenter veins. Stems branching near the base and rooting at nodes to form dense and extensive infestations. Dried whitish-tan grass may remain standing or matted in early winter.
Ascending to reclining, slender and wiry, up to 4 feet (120 cm) long, with alternate branching. Covered by overlapping sheaths with hairless nodes and internodes. Green to purple to brown. Aerial rootlets descend from lower nodes.
Alternate (none basal), projecting out from stem, lanceolate to oblanceolate, 2 to 4 inches (5 to 10 cm) long and 0.07 to 0.6 inch (2 to 15 mm) wide. Blades flat, sparsely hairy on both surfaces and along margins. Midvein whitish and off center. Throat collar hairy. Ligule membranous with a hairy margin.
July to October. Terminal, thin and spikelike raceme, to 3 inches (8 cm) long. Unbranched or with 1 to 3 lateral branches on an elongated wiry stem. Other thin racemes of self-pollinating flowers enclosed or slightly extending from lower leaf sheaths and flower/seeding before terminal racemes. Spikelets paired, with the outer stemmed and inner sessile.
August to December. Husked grain, seed head thin, grain ellipsoid, 0.1 inch (2.8 to 3 mm) long, with terminal seedstalks partially remaining during early winter.
Flourishes on alluvial floodplains and streamsides, mostly colonizing floodscoured banks, due to water dispersal of seed and flood tolerance. Also common at forest edges, roadsides and trailsides as well as damp fields, swamps, lawns and along ditches. Occurs up to 4,000 feet (1200 m) elevation. Very shade tolerant. Consolidates occupation by prolific seeding, with each plant producing 100 to 1,000 seeds that can remain viable in the soil for 3 years. Spreads on trails and recreational areas by seeds hitchhiking on hikers’ and visitors’ shoes and clothes.
nonnative crabgrass (Digitaria spp.) and native nimblewill (Muhlenbergia schreberi J.F. Gmel.), both having broad short leaves, but distinguished from Nepalese browntop by branching seed heads and stout stems. Also resembles whitegrass (Leersia virginica Willd.), which is a native perennial with flat, compressed seed heads. Also resembles wavyleaf basketgrass [Oplismenus hirtellus (L.) P. Beauv.] (nonnative invasive) and basketgrass [O. hirtellus (L.) P. Beauv. ssp. undulatifolius (Ard.) U. Scholz] (native), which form dense stands of similar appearance in similar habitats, but have wavy leaves and widely branching seed heads.
History and use
Native to temperate and tropical Asia, and first identified near Knoxville, TN, around 1919. Ground cover with little wildlife food value.
Found throughout the region with frequent and dense infestations in KY, VA, TN, and NC and spreading south through SC, MS, AL, GA, and into the panhandle of FL.
- Apply herbicide and mowing treatments to stop seed production.
- Hand pulling alone or hand pulling followed by a summer herbicide application result in the most plant diversity compared to broadcast glyphosate treatments, while control and diversity will only be maintained with repeated hand pulling.
- Treat when new plants are young to prevent seed formation, and be aware that early summer self-pollinated seeds are hidden inside the leaf sheaves.
- Clean shoes, clothes, dogs, and equipment of tiny seeds before leaving infested areas.
- Minimize disturbance within miles of where this plant occurs, and anticipate wider occupation when plants are present before disturbance.
- Infestations result in a widespread and dense layer of fine fuels in winter that can result in intense fires causing damage to native plants. Prescribed burning can promote spread of existing infestations..
Recommended control procedures
- Apply a glyphosate herbicide as a 0.5- to 2-percent solution in water (2 to 8 ounces per 3-gallon mix) with a surfactant in early summer; or apply Fusilade® DX or Plateau* (see label) in summer for situations that require more selective control and less impact on associated plants (hand weeding a month prior to these treatments will increase control and revegetation diversity).
- Repeat treatments for several years to control abundant germinating seeds. Mowing or pulling just before seed set will also prevent seed buildup in the soil seed bank. An early summer seed crop is hidden inside the leaf sheaves.
* Nontarget plants may be killed or injured by root uptake.