Japanese Stiltgrass (visible in the understory)
Microstegium vimineum · Warm-season, Annual, C4
Grass Family
Poaceae, Panicoideae
Grass Category
Invasive/Weed Grass
Variety / Cultivar
Wild-type (invasive species)
Hardiness Zones
USDA Zones 4-11; annual that dies back with the first frost but persists via heavy seed production.
About This Grass
A sprawling annual grass that reaches 1 to 3 feet in height. It has a bamboo-like appearance with a distinctive silvery midrib on the leaves. It thrives in low-light forest understories.
Blade Characteristics
Leaf blades are 1-3 inches long, lance-shaped, and asymmetric. A characteristic pale, reflective line (silvery midrib) runs down the center. Tips are pointed; vernation is rolled.
Root System
Shallow fibrous roots and weak stolons that root at the nodes. Does not form a deep root system, making it easy to pull but quick to spread.
Growing Information
Origin Region
Asia (China, India, Japan, Korea); invasive in Eastern North America
Growth Habit
Stoloniferous; sprawling and mat-forming; replaces native groundcover
Sunlight & Water Needs
Highly shade-tolerant but survives in full sun. Prefers moist soils, floodplains, and disturbed forest edges.
Mowing & Maintenance
Not typically mowed for turf; mowing in late summer before seed set (August/September) can help control spread. Extremely difficult to eradicate once established in seed bank.
Special Characteristics
Extreme shade tolerance; produces up to 1,000 seeds per plant; seeds remain viable for 3-5 years; allelopathic tendencies that inhibit other plants.
Ecological Information
Highly invasive; provides very little wildlife value; displaces native biodiversity and alters soil chemistry and fire cycles in forest ecosystems.