North America Native Plant

Hillebrand’s Flatsedge

Botanical name: Cyperus hillebrandii var. decipiens

USDA symbol: CYHID

Life cycle: perennial

Habit: grass

Native status: Native to Hawaii  

Synonyms: Cyperus decipiens Hillebr. (CYDE12)  âš˜  Mariscus hillebrandii (Boeckeler) T. Koyama ssp. decipiens (Hillebr.) T. Koyama (MAHID)   

Hillebrand’s Flatsedge: A Hawaiian Native Worth Knowing If you’re passionate about native Hawaiian plants, you’ve probably encountered many stunning endemic species. But have you met Hillebrand’s flatsedge? This unassuming sedge might not have the flashy flowers of native hibiscus, but it plays an important role in Hawaii’s natural landscape and ...

Rare plant alert!

Region: Conservation status by state

Status: S3T3: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Subspecies or variety is vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. ⚘

Hillebrand’s Flatsedge: A Hawaiian Native Worth Knowing

If you’re passionate about native Hawaiian plants, you’ve probably encountered many stunning endemic species. But have you met Hillebrand’s flatsedge? This unassuming sedge might not have the flashy flowers of native hibiscus, but it plays an important role in Hawaii’s natural landscape and deserves a spot in thoughtfully planned native gardens.

Meet the Plant

Hillebrand’s flatsedge (Cyperus hillebrandii var. decipiens) is a perennial sedge that’s endemic to the Hawaiian Islands. Like other members of the sedge family, it’s a grass-like plant with triangular stems – a key identifying feature that distinguishes sedges from true grasses. You might also see this plant listed under its scientific synonyms, including Cyperus decipiens or Mariscus hillebrandii ssp. decipiens, depending on which botanical reference you’re consulting.

Where You’ll Find It

This native sedge calls Hawaii home and only Hawaii. It’s found exclusively across the Hawaiian Islands, making it a true endemic treasure. As a plant that evolved specifically in Hawaiian conditions, it’s perfectly adapted to the islands’ unique climate and growing conditions.

Why Consider This Native Sedge?

There are several compelling reasons to include Hillebrand’s flatsedge in your native Hawaiian garden:

  • Authentic native landscaping: As an endemic species, it represents the true botanical heritage of Hawaii
  • Low-maintenance appeal: Once established, native sedges typically require minimal care
  • Ecosystem support: Native plants support local wildlife and contribute to healthy ecosystems
  • Water-wise gardening: Adapted to local rainfall patterns and soil conditions

A Word About Conservation

Before we dive into growing tips, there’s something important to know: Hillebrand’s flatsedge has a conservation status that deserves our attention. This means the plant may face some challenges in the wild, making responsible cultivation even more meaningful. If you choose to grow this species, make sure you source plants or seeds from reputable native plant nurseries that practice ethical collection methods.

Growing Hillebrand’s Flatsedge Successfully

Ready to welcome this native sedge into your garden? Here’s what you need to know:

Ideal Growing Conditions

  • Climate zones: USDA zones 10-12 (perfect for Hawaii’s tropical and subtropical conditions)
  • Light requirements: Full sun to partial shade
  • Soil needs: Moist to wet soils – this sedge appreciates consistent moisture
  • Drainage: While it likes moisture, ensure some drainage to prevent waterlogging

Perfect Garden Settings

Hillebrand’s flatsedge shines in several garden scenarios:

  • Native Hawaiian landscapes: Pairs beautifully with other endemic plants
  • Rain gardens: Excellent for areas that collect water runoff
  • Wetland restoration projects: Ideal for recreating natural wetland conditions
  • Pond or water feature margins: Creates natural-looking edges around water features

Planting and Care Tips

The good news is that native plants like Hillebrand’s flatsedge are generally easier to care for than non-native species, especially when planted in appropriate conditions:

  • Watering: Keep soil consistently moist, especially during establishment
  • Fertilizing: Native plants typically don’t need heavy fertilization – a light application of organic matter annually should suffice
  • Maintenance: Minimal pruning needed; remove any dead or damaged growth as needed
  • Establishment: Give new plants time to develop strong root systems before expecting rapid growth

Wildlife and Ecosystem Benefits

While Hillebrand’s flatsedge might seem humble compared to showy flowering plants, it serves important ecological functions. As a native sedge, it provides habitat and food sources for native insects and other small creatures. Its root system also helps with soil stabilization and water filtration – particularly valuable in wetland settings.

Is This Plant Right for Your Garden?

Hillebrand’s flatsedge is an excellent choice if you’re committed to native Hawaiian gardening and have the right growing conditions. It’s particularly well-suited for gardeners who:

  • Have naturally moist or wet areas in their landscape
  • Are creating rain gardens or bioswales
  • Want to support native Hawaiian ecosystems
  • Appreciate the subtle beauty of grass-like plants
  • Are involved in wetland restoration or conservation projects

However, this might not be the best choice if you’re looking for showy flowers or dramatic foliage. Its beauty lies in its natural, understated form and its ecological value rather than ornamental impact.

The Bottom Line

Hillebrand’s flatsedge represents the quiet beauty and ecological importance of Hawaii’s native flora. While it may not be the star of your garden, it can play a valuable supporting role in native landscapes, particularly in moist areas where many other plants struggle. By choosing to grow this endemic sedge responsibly, you’re not just adding an interesting plant to your garden – you’re participating in the preservation of Hawaii’s unique botanical heritage.

Remember to source your plants ethically and consider this sedge as part of a broader commitment to native Hawaiian gardening. Your local native plant society or extension office can help you find reputable sources and connect you with other native plant enthusiasts in your area.

Hillebrand’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 hillebrandii Boeckeler - Hillebrand'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