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Umbrella Flatsedge

Cyperus diandrus

Last reviewed: June 2026

Umbrella Flatsedge (Cyperus diandrus)
Photo: Owen Strickland / Wikimedia Commons (CC BY 4.0)

Toxicity unknown

Umbrella Flatsedge (Cyperus diandrus) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

full sun

Water

medium

Size

8"–24" H × 4"–12" W

Bloom

Jul, Aug, Sep

Native to

AL, CT, DE, IA and 19 more states

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Browse plants for this ecoregion

Central Great PlainsNorthwestern Great PlainsGreat PlainsWestern Corn Belt PlainsNorthern Lakes and ForestsNorth Central Hardwood ForestsDriftless AreaSoutheastern Wisconsin Till PlainsCentral Corn Belt PlainsSouthern Michigan/Northern Indiana Drift PlainsNortheastern HighlandsNortheastern Coastal ZoneNorthern Allegheny PlateauMiddle Atlantic Coastal PlainNorthern PiedmontRidge and ValleyInterior River Valleys and HillsAcadian Plains and HillsEastern Great Lakes LowlandsAtlantic Coastal Pine Barrens

Cyperus diandrus is a small annual sedge that forms compact clumps with thin, grass-like foliage. It produces small clusters of brownish flower heads from summer through early fall. This plant thrives in full sun with consistent moisture.

In an HOA neighborhood

Umbrella Flatsedge takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.

Works well in: backyard only.

  • Looks very much like a weed or wild grass
  • Annual nature means gaps in coverage
  • Inconspicuous flowers lack ornamental appeal

Wildlife value

This sedge provides seeds for small birds and offers nesting material. The dense growth habit can provide shelter for beneficial insects.

Common questions

How much sun does Umbrella Flatsedge need?
Umbrella Flatsedge grows best in full sun conditions.
When does Umbrella Flatsedge bloom?
Umbrella Flatsedge blooms in July, August, and September.
Where is Umbrella Flatsedge native?
Umbrella Flatsedge (Cyperus diandrus) is native to AL, CT, DE, IA and 19 more states, per vouchered herbarium specimen records and regional native plant society lists.
Is Umbrella Flatsedge HOA-friendly?
Umbrella Flatsedge takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

Ready to grow Umbrella Flatsedge? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.

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