An annual grass with thin, pale green, lance-shaped leaves that are 3 inches long. The midvein of the leaf is off-center and has a distinct silvery stripe of reflective hairs. Flower spikes form at the slender stem tips in late summer. Each plant produces hundreds of small, yellow-to-red seeds that can remain viable for five years. Blooms September through October.
Height: 1 to 3½ feet.
Currently found primarily in 11 counties in the southern part of the state.
Habitat and Conservation
Japanese stiltgrass is an invasive annual grass that occurs in a wide variety of habitats and is very tolerant of shade. Most often found in moist, disturbed areas including stream banks, river bluffs, floodplains, forest wetlands, moist woodlands, early successional fields, uplands, thickets, roadside ditches, and utility rights-of-way. Stiltgrass seems to prefer acidic to neutral soils that are high in nitrogen.
Invasive. Except for a few states in northern New England, Japanese stiltgrass has spread to every state east of the Mississippi and is considered invasive in 15 states. It is well adapted to low-light conditions, so it threatens native plants and habitats in open-to-shady and moist-to-dry locations. It forms dense patches, displacing and outcompeting native species for nutrients and light. In some cases, stiltgrass has been known to completely replace ground vegetation in three to five years.
Stiltgrass plants are annual: They die each fall and reproduce mainly by seed. This species also spreads vegetatively by forming roots at the nodes. The seed can be transported long distances by water or contaminated hay, seed mix, and soil. People can spread stiltgrass by carrying the seeds on their shoes, equipment, and vehicles.
First discovered in Tennessee in 1919, stiltgrass, also called eulalia, may have accidentally escaped as a result of its use as packing material for Chinese porcelain. Today, crates and packing material for imported products remain common vectors for accidental importation of unwanted organisms.
This species is unpalatable to wildlife; where white-tailed deer are overabundant, they may aid stiltgrass invasions by avoiding it and feeding on native plants. Stiltgrass also alters soil chemistry, which has been shown to reduce small-insect diversity and encourage the presence of mites.