Miscanthus sacchariflorus (Amur Silvergrass)
|Also known as:||Silver Banner-grass|
|Habitat:||part shade, sun; average to moist, disturbed soil; roadsides, ditches, fields, lawns, woodland edges|
|Fruiting season:||September - October|
|Plant height:||2 to 8 feet|
|Wetland Indicator Status:||GP: FAC MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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A single raceme 6 to 12+ inches long at the tip of the stem, with 8 to 40 branches that are mostly ascending to erect, the whole plume often nodding to one side. Spikelets (flower clusters) are in pairs along a branch, each spikelet 4 to 6 mm (to ¼ inch) long with 1 or 2 florets, the lower sterile and the upper fertile.
At the base of a spikelet is a pair of bracts (glumes), both similar in size and shape, 4 to 6 mm long, longer than the florets, thin and papery, narrowly lance-elliptic tapering to a pointed tip, awnless, the lower glume densely covered with straight, white hairs around the base and at the tip, more sparsely on the surface and along the edges, the hairs 2 to 4 times as long as the glume; the upper glume hairy mostly on the upper half. Florets are surrounded by a pair of bracts (lemma and palea), the lemma somewhat shorter than the glumes, translucent whitish, short-hairy along the edges, awnless; the sterile palea is inconspicuous, the fertile palea is about half as long as the lemma.
Leaves and stems:
Leaves are alternate, 8 to 30 inches long, 5 to 30 mm (to 1+ inch) wide, mostly flat, usually arching, fairly evenly distributed along the stem, hairless except on the upper surface at the base of the blade. The midvein is prominent and whitish. Leaves turn orange in fall.
Sheaths are hairless. The ligule (membrane where the leaf joins the sheath) is up to 1 mm long, more or less straight across and fringed with hairs up to 2 mm long. Nodes are covered in appressed hairs. Stems are unbranched, hairless, erect, single or multiple from the base. Dense colonies form from elongating, scaly rhizomes.
The entire spikelet drops off at maturity, leaving a naked stalk behind. Plants are not self-compatible, so viable seed within a single colony of clones is not often produced.
Amur Sivergrass came to North America as an ornamental and occasionally escapes cultivation, showing up in moist ditches, woodland edges and clearings. It can form large, dense monocultures that crowd out other plants and is thus considered potentially invasive by the MN DNR and UM Extension; its spread has been recorded on EDDMapS. If you see it outside of a garden, report it!
There is another Miscanthus species, M. sinensis (Chinese Silvergrass), that is apparently equally as problematic but is not known to be in Minnesota (yet); the closest sightings are in northern Illinois. The hairs on its spikelets are less than twice as long as the glume and their color ranges from white to yellowish to reddish, and lemmas have conspicuous awns. Vaguely similar is Phragmites, which has hairless glumes, awned lemmas, and hairs are only around the base of a floret.
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- Amur Silvergrass plants
- Amur Silvergrass plants
- roadside Amur Silvergrass
- Amur Silvergrass running amok
Photos by K. Chayka taken at Fort Snelling State Park and in Anoka County. Other photos courtesy Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?