Beckmannia syzigachne (American Slough Grass)

Plant Info
Also known as:
Family:Poaceae (Grass)
Life cycle:annual
Habitat:sun; wet soil; marshes, shores, stream banks, wet ditches
Fruiting season:June - August
Plant height:8 to 36 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct Cluster type: panicle Cluster type: raceme Cluster type: spike

[photo of flowering spikes] Raceme-like branching cluster 3 to 12 inches long at the tip of the stem, the 4 to 15 main branches appressed to ascending, with 1 to several appressed branchlets per branch, each branchlet up to about 3/8 inch (1cm) long. Spikelets (flower clusters) are about 1/8 inch (2 to 3.5mm) long, flattened, round to broadly oval with an abruptly pointed tip, and have a single fertile floret, occasionally also with a single, minute, sterile floret. Spikelets are arranged on one side of the rachis (stalk), tightly packed in 2 rows, the spikelets overlapping. All parts are hairless.

[photo of panicle branches] At the base of a spikelet is a pair of bracts (glumes) that are firm, light green with thin translucent edging, D-shaped in outline, pointed at the tip, 3-veined, both the same size and the pair completely enclosing the floret except the very tip. Surrounding a floret are a pair of bracts (lemma and palea), the lemma lance-elliptic, tapering to a pointed tip, 5-veined and as long as or slightly longer than the glumes. The palea is slightly shorter than the lemma and 2-veined.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of sheath, ligule and node] Leaves are 3 to 8 inches long, 1/8 to 3/8 inch (4 to 10mm) wide, flat, the surfaces hairless but rough textured. Sheaths are hairless with thin, translucent white edging, and mostly overlap near the tip. Basal leaves are few. The ligule (membrane where the leaf joins the sheath) is a loose, thin, membranous band up to about 3/8 inch (3 to 11mm) long, triangular or ragged along the edge, and often folded back. Nodes are hairless and green to purplish. Stems are erect, hairless, single or a few from the base, forming loose clumps.

Fruit: Fruit type: seed without plume

[photo of mature florets] Spikelets ripen to light brown, the spikelets shedding as each grain matures, leaving a naked stem behind. Grains (seeds) are light to medium brown and less than 2 mm long.


American Slough Grass is a common grass of open, wet places and is native to both North America and Asia. Its unique spikelet shape and arrangement are distinctive. Note that other references state the ligules are hairy, but this was not an obvious trait.

Native Plant Nurseries, Restoration and Landscaping Services ↓

Map of native plant resources in the upper midwest

  • Landscape Alternatives
  • ReWild Native Gardens
  • Shop for native seeds and plants at!
  • Shooting Star Native Seeds - Native Prairie Grass and Wildflower Seeds
  • Morning Sky Greenery - Native Prairie Plants

More photos

Photos courtesy Peter M. Dziuk taken in Kittson, Marshall and Swift counties.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Alexandra W - South entral Polk Co. Glacial Ridge National Wildlife Refuge
on: 2017-09-19 15:10:01

American slough grass was growing along the margins of a wet meadow on Glacial Ridge NWR.

Post a comment

Note: All comments are moderated before posting to keep the riff-raff out. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission.

For info on subjects other than plant identification (gardening, invasive species control, edible plants, etc.), please check the links and invasive species pages for additional resources.


Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because Id like to keep the focus of this web site centered on Minnesota. Thanks for your understanding.