Japanese Stiltgrass
Microstegium vimineum · Warm-season, Annual, C4
Grass Family
Poaceae, Subfamily Panicoideae, Tribe Andropogoneae
Grass Category
Invasive/Weed Grass
Variety / Cultivar
None specified; wild-type invasive population
Hardiness Zones
USDA Zones 4-11; dies back completely in winter but persists via a massive soil seed bank.
About This Grass
A sprawling, pale green annual grass that forms dense monocultures. It typically grows 1-3 feet tall if left unmowed. In autumn, it may turn a reddish or purplish color before dying back after the first frost.
Blade Characteristics
Wide (5-15mm), short (2-8cm in length), lance-shaped, pale green. A distinctive reflective silver stripe (midrib) runs offset down the center of the leaf surface. Tips are pointed; vernation is rolled.
Root System
Shallow and fibrous; easily hand-pulled. It utilizes adventitious roots from stem nodes to spread rapidly across the soil surface.
Growing Information
Origin Region
Native to Asia (China, India, Japan, Korea). Highly invasive in Eastern and Southern United States.
Growth Habit
Stoloniferous and sprawling; develops roots at node points where they touch the soil, forming dense carpets.
Sunlight & Water Needs
Highly shade-tolerant but also grows in full sun. Prefers moist soils and riparian areas but is highly adaptable to various soil pH levels.
Mowing & Maintenance
Not a maintained grass. If mowed, it adapts by flowering closer to the ground. Targeted for eradication via pre-emergent herbicides or frequent low-cutting before seed set in late summer.
Special Characteristics
Extremely high shade tolerance for a C4 grass; produces up to 1,000 seeds per plant that remain viable in soil for 3-5 years; displaces native vegetation.
Ecological Information
Invasive status in North America; provides little to no nutritional value for local wildlife; disrupts native plant communities and alters soil chemistry; often spreads via contaminated soil or footwear.