Amur silvergrass (Miscanthus sacchariflorus)

Synonyms: Triarrhena sacchariflora, Imperata sacchariflora

Common Names: Creeping miscanthus, silver banner grass, plume grass

Description:

Amur silvergrass (Miscanthus sacchariflorus) is a tall ornamental grass from the cool-temperate regions of eastern Asia, planted in yards for its showy silvery fall plumes [1][2]. It escapes from plantings and spreads by creeping underground stems into roadsides, woodland edges, and clearings, where it forms dense single-species stands [1]. MISIN tracks it because those stands crowd out native plants and are hard to remove once the underground stems take hold [1].

Habit:

Amur silvergrass is a warm-season perennial grass that grows 6 to 8 feet tall and forms dense, spreading mats [1][2]. Its leaves are long and arching, less than an inch wide, with one feature that makes it easy to name: a distinct whitish line running down the center of each leaf [1][2]. Where the leaf meets the stem there is a fringe of hairs [1]. In fall it produces silky, silvery, plume-like flower heads that look like dense corn tassels and arch to one side of the stalk [1][2]. It is easiest to spot in late summer and fall when the silvery plumes are out and stand well above surrounding plants [1].

At-a-glance cues:

1. Tall grass, 6 to 8 feet, forming dense spreading mats [1][2]
2. Arching leaves under 1 inch wide with a distinct whitish line down the center [1][2]
3. A fringe of hairs where the leaf meets the stem [1]
4. Silky, silvery fall plumes like dense corn tassels, arching to one side [1][2]

Leaves:

1. Long, arching, and less than 1 inch wide [1][2]
2. Marked by a distinct whitish line down the center (midrib) ? a key clue [1][2]
3. A fringe of hairs where the leaf base meets the stem [1]
4. Edges can be sharp; wear gloves when handling [1]

Stems:

1. Herbaceous (not woody) warm-season grass stems, 6 to 8 feet tall, in dense stands [1][2]
2. Spreads by long, horizontal underground stems (rhizomes) that form expanding mats [1][2]
3. New stands often grow from rhizome or root pieces moved in soil [1]

Flowers:

1. Silky, silvery, plume-like flower heads at the tops of the stems [1][2]
2. Resemble dense corn tassels and arch to one side of the stalk [1][2]
3. Bloom in fall [1][2]
4. Florets lack the small bristles (awns) found on Chinese silvergrass [1]

Fruit and seeds:

1. Seeds form in the plume-like flower heads after fall flowering [1]
2. In cooler northern climates the plant sets little viable seed, so most spread is by underground stems, not seed [1]
3. Where seed is produced, it can be carried by wind [2]
4. Most new patches start from rhizome or root fragments moved in soil [1]

Habitat:

Amur silvergrass invades sunny to partly shaded, disturbed places ? roadsides, woodland borders, old fields, and clearings ? and spreads more easily in moist ground than in dry [1][2]. It is native to the cool-temperate regions of eastern Asia and was brought to the United States as an ornamental grass [1][2]. From yard and roadside plantings it has escaped into natural areas across the Midwest and other parts of North America [1].

Reproduction:

Amur silvergrass spreads mainly underground [1]. Its long, creeping rhizomes push outward and send up new stems, so a single clump slowly widens into a dense mat [1][2]. New patches most often start when pieces of root or rhizome are moved in soil ? on equipment, in fill dirt, or in dumped yard waste ? and take root somewhere new [1]. In cooler northern areas the plant makes little viable seed, but where it does set seed, the seed can blow on the wind to start new plants [1][2].

Because the plant comes back from its underground stems, the key to control is removing or exhausting those rhizomes [1]. Dig out every piece of root and rhizome, or cut and mow the stand repeatedly over several years before it can rebuild ? and remove plants before the fall plumes can shed any seed [1].

Impact and Damage:

Amur silvergrass is not poisonous to people or pets, and it is grown on purpose in gardens for its plumes [1]. The problem is how it spreads once it escapes [1]. Its creeping underground stems build dense, mat-forming stands that grow into single-species patches, shading and crowding out the native grasses and wildflowers that would otherwise grow there and lowering the variety of plants in a natural area [1][2]. Those thick stands also leave little room or food value for the native wildlife that depend on diverse native vegetation [1]. Once established, the rhizome mats are difficult and slow to remove, so a small escaped patch can become a large, persistent problem [1].

Similar species:

Amur silvergrass is one of several tall grasses with showy plumes that are mixed up with one another. The whitish leaf midrib and the colony-forming, mat-like growth are the best clues.

Chinese silvergrass (Miscanthus sinensis) is the closest look-alike ? a closely related ornamental grass that is also invasive. It grows in tight clumps with short underground stems rather than spreading mats, and its flower florets carry tiny bristles (awns) that Amur silvergrass lacks [1].

Common reed (Phragmites australis) is another tall, plumed invasive grass of wet edges and ditches. It grows much taller, often over 12 feet, with hollow stems and large, feathery, purplish-to-tan plumes, and it does not have the single whitish leaf midrib of Amur silvergrass [1].

Ravenna grass (Tripidium ravennae) is a tall ornamental plume grass sometimes called hardy pampas grass. It grows in large clumps rather than creeping mats and has grayish, more upright plumes [1].

Big bluestem (Andropogon gerardii) is a native prairie grass of similar height. Its seed heads split into three finger-like branches (the "turkey-foot") rather than forming a single silvery plume, and it grows in bunches rather than dense creeping mats [1].

Monitoring and rapid response:

Signs to watch for:

1. A tall grass, 6 to 8 feet, in a dense, spreading patch [1][2]
2. Arching leaves under an inch wide with a distinct whitish line down the center [1][2]
3. Silky, silvery plumes like dense corn tassels in late summer and fall, arching to one side [1][2]
4. Patches expanding outward from an old planting, or springing up where soil was moved [1]

What you can do:

1. Dig out small plants and patches, removing every piece of root and rhizome ? fragments left behind resprout [1]
2. For larger stands, cut or mow as short as possible and repeat through the season and over several years to wear down the underground stems [1]
3. Cut and bag the plumes before the fall, in case any seed is produced, and dispose of plants and rhizomes in the trash ? do not compost them or move soil that contains rhizome pieces [1]
4. Wear gloves and long sleeves ? the leaf edges can be sharp [1]
5. Do not plant Amur silvergrass, and remove existing plantings near natural areas [1]
6. Natural area crews can clear larger stands by repeated cutting or mowing across the site over multiple years and should remove small, outlying patches first before they merge [1]

When to call a professional:

1. Large, well-established stands with extensive rhizome mats that keep regrowing after cutting [1]
2. Infestations along roadsides, rights-of-way, or other large or hard-to-reach sites [1]
3. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Minnesota Department of Natural Resources. Creeping miscanthus / Amur silver grass (Miscanthus sacchariflorus). dnr.state.mn.us
2. University of Minnesota Extension. Creeping miscanthus (Miscanthus sacchariflorus). extension.umn.edu
3. USDA NRCS PLANTS Database. Miscanthus sacchariflorus (Maxim.) Hack. (MISA). plants.usda.gov

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