North America Native Plant

Round Sawsedge

Botanical name: Gahnia aspera globosa

USDA symbol: GAASG

Life cycle: perennial

Habit: grass

Native status: Native to Hawaii  

Synonyms: Gahnia globosa H. Mann (GAGL)   

Round Sawsedge: A Hawaiian Native Sedge Worth Knowing If you’re exploring native Hawaiian plants for your garden, you might have come across the intriguingly named round sawsedge (Gahnia aspera globosa). This perennial sedge is a true Hawaiian original – an endemic species that calls the islands its only home in ...

Round Sawsedge: A Hawaiian Native Sedge Worth Knowing

If you’re exploring native Hawaiian plants for your garden, you might have come across the intriguingly named round sawsedge (Gahnia aspera globosa). This perennial sedge is a true Hawaiian original – an endemic species that calls the islands its only home in the world.

What is Round Sawsedge?

Round sawsedge belongs to the sedge family (Cyperaceae), making it a grass-like plant rather than a true grass. Like its sedge cousins, it’s a monocot with triangular stems and narrow leaves. The botanical name Gahnia aspera globosa has a synonym you might encounter: Gahnia globosa H. Mann, named after the botanist who first described it.

As a perennial plant, round sawsedge returns year after year, making it a potentially valuable addition to sustainable landscape designs that celebrate Hawaii’s unique flora.

Where Does Round Sawsedge Grow?

This special sedge is found exclusively in Hawaii, making it a true island endemic. Its natural range is limited to the Hawaiian Islands, where it has evolved in isolation over thousands of years.

The Challenge of Growing Round Sawsedge

Here’s where things get a bit tricky for the home gardener: detailed cultivation information for round sawsedge is surprisingly scarce. This isn’t uncommon with Hawaiian endemic plants, many of which haven’t been extensively studied for home gardening applications.

What we do know is that as a native Hawaiian sedge, it likely prefers:

  • Conditions similar to its natural habitat
  • Well-draining soil (typical for most sedges)
  • Climate conditions found in Hawaii

Why Consider Native Hawaiian Plants?

Even though growing information is limited, there are compelling reasons to be interested in round sawsedge and other Hawaiian natives:

  • Ecological authenticity: Native plants support local ecosystems and wildlife
  • Climate adaptation: They’re naturally suited to Hawaiian conditions
  • Cultural significance: Hawaiian natives connect us to the islands’ natural heritage
  • Sustainability: Once established, natives typically require fewer resources

A Word of Caution

If you’re interested in growing round sawsedge, it’s crucial to source plants responsibly. Given the limited information available about this species, it’s possible it could be rare or have specific conservation needs. Always purchase from reputable native plant nurseries and never collect plants from the wild.

Moving Forward with Native Hawaiian Gardening

While we may not have all the cultivation details for round sawsedge figured out, this highlights an exciting opportunity for Hawaiian gardeners and native plant enthusiasts. By supporting research into native Hawaiian plants and working with local botanists and native plant societies, we can help expand knowledge about species like round sawsedge.

If you’re passionate about native Hawaiian gardening, consider connecting with local native plant groups, botanical gardens, or university extension programs. They may have more specific information about growing this unique sedge or can point you toward similar native alternatives that are better understood.

Sometimes the most rewarding garden plants are those that challenge us to learn something new – and round sawsedge certainly fits that bill!

Round Sawsedge

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

Gahnia J.R. Forst. & G. Forst. - sawsedge

Species

Gahnia aspera Spreng. - round sawsedge

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