Japanese Stiltgrass
Microstegium vimineum · Warm-season, Annual, C4
AI-generated identification · may be incorrect
Grass Category
Invasive/Weed Grass, Wetland/Riparian Grass
Hardiness Zones
USDA Hardiness Zones 5 to 9, thriving particularly well in the eastern and southeastern United States where summer humidity and moisture are high.
Grass Family
Poaceae, subfamily Panicoideae
Variety / Cultivar
Not applicable (wild species with no standard cultivated varieties)
About This Grass
An annual grass with a sprawling, delicate habit, growing up to 2-3 feet tall or long. Leaves are light green, lance-shaped, and asymmetrical. Forms dense, uniform stands that outcompete native vegetation. Produces slender terminal and axillary racemes with spikelets in late summer.
Blade Characteristics
Blades are flat, relatively short (1 to 3 inches long), and wider (5 to 15 mm) with a distinctive silvery line of reflective hairs along the midrib on the upper surface. Tip is pointed, vernation is rolled, and ligule is a short membrane.
Root System
Shallow, fibrous root system with weak anchorage, making it easy to pull up by hand. Spreads primarily via prolific seed production and nodes rooting along the ground.
Growing Information
Origin Region
Native to Asia (China, Japan, Korea, India, and parts of Southeast Asia); naturalized extensively in the eastern United States
Growth Habit
Stoloniferous, spreading and rooting at the lower nodes to form dense, sprawling mats
Sunlight & Water Needs
Highly shade tolerant, frequently found in forest understories, along stream banks, and in damp, disturbed soils. Prefers moist conditions and moderate to low light, though it can survive in full sun if moisture is sufficient.
Mowing & Maintenance
Considered a severe weed in lawns and natural areas; managed by frequent low mowing before seed set, hand pulling, or herbicide application. Maintenance involves eradication rather than cultivation.
Special Characteristics
Exceptional shade tolerance, highly invasive nature, rapidly colonizes disturbed habitats, tolerates acidic soils, low wear tolerance as an annual weed, and reproduces exclusively by seed.
Ecological Information
Highly invasive introduced species in North America. Negatively impacts native plant communities and forest regeneration. Provides minimal wildlife value compared to native flora and alters natural soil chemistry and fire regimes.