Japanese stiltgrass is an annual grass in the Poaceae family and is native to Japan, Korea, China, Malaysia, and India. It was first found in the United States at Knoxville, Tennessee in 1919, and was collected in western North Carolina in 1933. By 1964, the grass had spread to 35 counties in North Carolina, and by 1972, it had been found in 14 eastern states. It was collected in Arkansas 1978. Stiltgrass is colonial in nature, rooting from the nodes, and can form dense monotypic stands. Reproduction is exclusively from seed, which are dispersed primarily by animals, flooding, and deposition with fill dirt. The plant is highly invasive, spreading rapidly into disturbed lowland areas, where it totally displaces native plant communities. In fertile sites Japanese stiltgrass can replace competing ground vegetation within 3-5 years. It is a shade-tolerant plant, which can survive and reproduce readily beneath a full forest canopy. Stiltgrass has been found at elevations greater than 3,800 ft. Microstegium is common in areas of natural and artificial disturbance in flood plains and along stream banks and other lowland areas throughout most of North Carolina. The plant also can invade undisturbed areas if brought in by animals or flooding. Deer avoid microstegium, which gives it a significant competitive advantage in over-browsed sites.

Stiltgrass is a sprawling, branched annual grass, which may grow to a height of 24-39 in. Stems are smooth and may be nearly 5 ft. long. The leaves are alternate, lance-shaped, about 4 in. long and half an inch wide, and have a sparse pubescence on both surfaces. Flowers occur in terminal racemes, which may be solitary or in a set of two or three. Spikelets occur are in pairs, one sessile and one pedicellate, and 4.5-5mm (0.17-0.2 in) long. Blooming generally occurs in August through September. Seeds are yellow to red and mature in September through October. Seed production may occur in heavily shaded sites where light levels as low as 5% of full sunlight. Each plant may produce from 100-1,000 seeds that remain viable in the soil for five or more years.