North America Non-native Plant

Owan’s Flatsedge

Botanical name: Cyperus owanii

USDA symbol: CYOW2

Life cycle: perennial

Habit: grass

Native status: Non-native, reproduces and persists in the wild in the lower 48 states  

Owan’s Flatsedge: A Lesser-Known Sedge for Specialized Gardens If you’ve stumbled across the name Owan’s flatsedge (Cyperus owanii) in your plant research, you’re looking at quite the botanical mystery! This perennial sedge is one of those plants that keeps a low profile in the gardening world, and for good reason ...

Owan’s Flatsedge: A Lesser-Known Sedge for Specialized Gardens

If you’ve stumbled across the name Owan’s flatsedge (Cyperus owanii) in your plant research, you’re looking at quite the botanical mystery! This perennial sedge is one of those plants that keeps a low profile in the gardening world, and for good reason – there’s surprisingly little information available about its garden potential.

What is Owan’s Flatsedge?

Owan’s flatsedge belongs to the sedge family (Cyperaceae), making it a grass-like plant that’s actually more closely related to rushes than true grasses. Like other sedges, it’s a perennial that can handle both wet and dry conditions, earning it a facultative wetland status in the arid western United States.

Where Does It Grow?

Currently, Cyperus owanii has been documented growing in California, where it’s established as a non-native species that reproduces on its own in the wild. This sedge originally hails from elsewhere but has found a way to make itself at home in the Golden State’s diverse landscapes.

Should You Plant Owan’s Flatsedge?

Here’s where things get interesting (or frustrating, depending on your perspective). Despite being established in California gardens and wild spaces, detailed horticultural information about Cyperus owanii is surprisingly scarce. We don’t have reliable data on:

  • Specific growing requirements
  • Mature size and appearance
  • USDA hardiness zones
  • Care and maintenance needs
  • Wildlife and pollinator benefits

This lack of information makes it challenging to recommend for most home gardens, especially when there are so many well-documented native alternatives available.

Better Native Alternatives

If you’re drawn to the idea of growing sedges in your garden, consider these fantastic native options instead:

  • California sedge (Carex californica) – Perfect for shade gardens with consistent moisture
  • Dune sedge (Carex pansa) – Excellent for coastal areas and lawn alternatives
  • Berkeley sedge (Carex tumulicola) – Great for slopes and naturalized areas
  • Foothill sedge (Carex tumulicola) – Drought-tolerant once established

The Bottom Line

While Owan’s flatsedge isn’t considered invasive or problematic, the lack of horticultural information makes it a risky choice for most gardeners. Why experiment with an unknown quantity when you could plant well-researched native sedges that support local ecosystems and come with proven growing guides?

If you’re a plant collector or researcher specifically interested in Cyperus owanii, proceed with caution and consider reaching out to local botanical institutions or native plant societies for guidance. For everyone else, those beautiful native sedge alternatives will give you much more predictable (and beneficial) results in your landscape!

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

FAC

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

Owan’s 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 owanii Boeckeler - Owan's flatsedge

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