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Olney's Threesquare

Schoenoplectus americanus

In the Carolinas and Georgia, found in tidal freshwater to brackish marshes. Weakley, Flora of the Southeastern United States (2025), Carolinas & Georgia edition What its natural habitat tells you

45
Good

Native to Louisiana (estimated). How scores work Is it native here?

Profile 76%

Height
It has erect, sharply triangular and deeply concave-sided culms growing up to 5 feet in height [10,21].
Light
Partial shade, Full sun
Soil moisture
Wet to standing water
Will it fit your yard?

At a glance

Life cycle
Perennial
Bloom
May to June
Fruiting season
June to September

Not yet recorded · Spread · Leaves

Recorded in 11 Louisiana parishes.

Natural habitats

Places it grows wild. Not a planting requirement. Each habitat page lists the plants and wildlife also found there.

Salt and brackish marshes

Coastal marshes flooded by salty or brackish tides.

All habitats

Ecological relationships

Who uses this plant?

What these records mean

11CaterpillarsGenus host records with ranges including LA

Genus host records with ranges including LA · Scirpus

  • Bactra furfuranaRush Bactra
  • Bactra verutanaJavelin Moth
  • Euphyes dionDion Skipper, Sedge Skipper
  • Globia oblongaOblong Sedge Borer Moth, Large Noagria
  • Ledaea perditalisLost Owlet, 3-Stripe Cephalanthus caterpillar, Buttonbush Owlet
  • Bactra maiorina
  • Cosmopterix attenuatella
  • Cosmopterix ebriola
  • Cosmopterix scirpicola
  • Donacaula dispersella
Show all 11
  • Thopeutis forbesellus
Shropshire & Tallamy 2025, Lepidoptera of North America north of Mexico, ZooKeys 1261 (ODbL)
0BeesSoutheastern regional records
0Specialist beesPollen specialists
27BirdsRecorded genus food-resource interactions; not a state feeding claim

Recorded genus food-resource interactions; not a state feeding claim · Scirpus

  • Agelaius phoeniceusRed-winged Blackbird
  • Anas platyrhynchosMallard
  • Anthus rubescensAmerican Pipit
  • Aythya affinisLesser Scaup
  • Aythya americanaRedhead
  • Aythya collarisRing-necked Duck
  • Aythya marilaGreater Scaup
  • Aythya valisineriaCanvasback
  • Bucephala clangulaCommon Goldeneye
  • Bucephala islandicaBarrow's Goldeneye
Show all 27
  • Calcarius lapponicusLapland Longspur
  • Calcarius pictusSmith's Longspur
  • Cygnus buccinatorTrumpeter Swan
  • Cygnus columbianusTundra Swan
  • Fulica americanaAmerican Coot
  • Gallinula galeataCommon Gallinule
  • Loxia curvirostraRed Crossbill
  • Mareca americanaAmerican Wigeon
  • Mareca streperaGadwall
  • Molothrus aterBrown-headed Cowbird
  • Oxyura jamaicensisRuddy Duck
  • Plectrophenax nivalisSnow Bunting
  • Porzana carolinaSora
  • Rallus limicolaVirginia Rail
  • Spatula cyanopteraCinnamon Teal
  • Spizelloides arboreaAmerican Tree Sparrow
  • Sturnus vulgarisEuropean Starling
Hurlbert, Olsen, Sawyer & Winner 2021, Avian Diet Database, Scientific Data 8: 260 (CC0)

Direct food only: birds recorded eating this genus across North America. Caterpillars on host plants also feed nesting birds. NC Native Plant Society: butterfly gardening

No records yet · Ants · Beetles · Flies · Adult butterflies / moths · Other wasps · Other insects

Growing and identification

Plant details

Family
Cyperaceae
Flower color
Yellow or brown
Fruit begins
June
Fruit ends
September

Safety has not been reviewed for this plant; check toxicity and thorns before planting.

Growing sources and scope
Also known as

Scirpus olneyi Gray; bulrush

Conservation status

Louisiana rankSNR
Global rankG5
LA statusNot verified
Federal statusNot verified

Conservation source Global and federal source

In your garden

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Sources