Nepalese Browntop
Microstegium vimineum (Trin.) A. Camus

Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS–62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.

Synonyms: Japanese grass, Mary’s grass, basketgrass

Plant. Sprawling, annual grass, 0.5 to 3 feet (15 to 90 cm) in height. Flat short leaf blades, with off-center veins. Stems branching near the base and rooting at nodes to form dense and extensive infestations. Dried whitish-tan grass remains standing in winter.

Stem. 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.

Leaves. 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.

Flowers. August to October. Terminal, thin and spikelike raceme, to 3 inches (8 cm) long. Unbranched or with one to three lateral branches on an elongated wiry stem. Spikelets paired, with the outer stemmed and inner sessile.

Seeds. September to December. Husked grain, seed head thin, grain ellipsoid, 0.1 inch (2.8 to 3 mm) long, with seedstalks partially remaining during winter.

Ecology. Flourishes on alluvial floodplains and streamsides, mostly colonizing flood-scoured 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 5 or more years. Spreads on trails and recreational areas by seeds hitchhiking on hikers’ and visitors’ shoes and clothes.

Resembles crabgrass, Digitaria spp., and 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 perennial with flat, compressed 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.

Recommended control procedures:

• Apply a glyphosate herbicide as a 2-percent solution in water (8 ounces per 3-gallon mix) with a surfactant in late summer. Or, apply Vantage (see label) for situations that require more selective control and less impact on associated plants.
• Repeat treatments for several years to control abundant germinating seeds. Mowing or pulling just before seed set in September will prevent seed buildup.

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