North America Native Plant

Fourangle Flatsedge

Botanical name: Cyperus tetragonus

USDA symbol: CYTE5

Life cycle: perennial

Habit: grass

Native status: Native to the lower 48 states  

Fourangle Flatsedge: A Humble Native Sedge for Wet Spots If you’ve got a soggy spot in your yard that leaves you scratching your head, let me introduce you to a quiet champion of wet places: fourangle flatsedge (Cyperus tetragonus). This unassuming native sedge might not win any beauty contests, but ...

Fourangle Flatsedge: A Humble Native Sedge for Wet Spots

If you’ve got a soggy spot in your yard that leaves you scratching your head, let me introduce you to a quiet champion of wet places: fourangle flatsedge (Cyperus tetragonus). This unassuming native sedge might not win any beauty contests, but it’s exactly the kind of hardworking plant that can turn your landscaping challenges into success stories.

What Exactly Is Fourangle Flatsedge?

Fourangle flatsedge is a perennial sedge native to the lower 48 states. Don’t let the name fool you – while it’s called a flatsedge, it’s actually a grass-like plant in the sedge family (Cyperaceae). Think of sedges as the understated cousins of grasses, often found hanging out in wetter spots where regular grasses would throw in the towel.

This native plant has made itself at home across a impressive range of states, including Alabama, Arizona, Florida, Georgia, Louisiana, Mississippi, New Mexico, North Carolina, and South Carolina. That’s quite the geographic spread for such a modest little plant!

Why Consider Fourangle Flatsedge for Your Garden?

Here’s where this little sedge really shines – its adaptability to different moisture conditions. Depending on your region, fourangle flatsedge can handle everything from wetland conditions to drier upland spots:

  • In the Arid West and Western Mountains regions, it typically grows in non-wetlands but can tolerate some moisture
  • In the Atlantic and Gulf Coastal Plain, Eastern Mountains and Piedmont, and Great Plains regions, it’s equally happy in wet or dry conditions

This flexibility makes it perfect for those tricky transition zones in your yard – you know, the spots that are sometimes soggy, sometimes dry, and always difficult to plant.

Where Does Fourangle Flatsedge Fit in Your Landscape?

Think of fourangle flatsedge as nature’s problem-solver. It’s ideal for:

  • Rain gardens and bioswales
  • Naturalized areas and native plant gardens
  • Wetland restoration projects
  • Ground cover in challenging wet spots
  • Transitional zones between wet and dry areas

While it won’t give you showy flowers or dramatic foliage, it provides that essential filler role that every good landscape design needs. It’s the plant equivalent of a reliable supporting actor – not stealing the show, but making everything else look better.

Growing Fourangle Flatsedge Successfully

The good news about fourangle flatsedge is that it’s refreshingly low-maintenance. As a native plant, it’s already adapted to your local conditions, which means less fussing for you.

Growing Conditions:

  • Thrives in USDA hardiness zones 7-10
  • Prefers moist to wet soils but adapts to various moisture levels
  • Grows well in full sun to partial shade
  • Tolerates periodic flooding

Planting and Care Tips:

  • Plant in spring after the last frost
  • Space plants according to how quickly you want coverage – they’ll spread naturally
  • Water regularly the first year to establish roots
  • Once established, it’s quite drought-tolerant (though it prefers consistent moisture)
  • No fertilizer needed – native plants prefer lean conditions
  • Spreads by underground rhizomes, so give it room to naturalize

Wildlife and Ecosystem Benefits

While fourangle flatsedge might not be a pollinator magnet like some showier natives, it plays important supporting roles in the ecosystem. The seeds provide food for birds, and the plant structure offers habitat for small wildlife. In wetland areas, it helps with erosion control and water filtration – nature’s own little water treatment system.

The Bottom Line

Fourangle flatsedge isn’t going to be the star of your garden Instagram posts, but it might just be the unsung hero your landscape needs. If you’re dealing with challenging wet spots, want to support native ecosystems, or simply need a reliable, low-maintenance ground cover, this humble sedge deserves a spot on your plant list.

Sometimes the best garden solutions come in the most unassuming packages. Fourangle flatsedge proves that you don’t need flashy flowers or dramatic foliage to be a valuable addition to a native landscape – sometimes, being dependable and well-adapted is exactly what your garden ordered.

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" matching plants to their ideal growing conditions, so they'll thrive with less work and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection is. While tags list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. Surprisingly, many popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. Also, it helps you make smarter gardening choices and grow healthy plants with less care and feeding, saving you time, frustration, and money while producing an attractive garden with greater ecological benefits.

Regions
Status
Moisture Conditions

Arid West

FACU

Facultative Upland - Plants with this status usually occurs in non-wetlands but may occur in wetlands

Atlantic and Gulf Coastal Plain

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Eastern Mountains and Piedmont

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Great Plains

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Western Mountains, Valleys, and Coast

FACU

Facultative Upland - Plants with this status usually occurs in non-wetlands but may occur in wetlands

Fourangle Flatsedge

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Cyperaceae Juss. - Sedge family

Genus

Cyperus L. - flatsedge

Species

Cyperus tetragonus Elliott - fourangle flatsedge

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA