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Coastal flatsedge

Cyperus pennatiformis

Coastal flatsedge
Photo: Forest & Kim Starr, CC BY 3.0

Coastal flatsedge is a rare, federally endangered sedge endemic to Hawaii, growing in coastal habitats on Maui, Kauai and Laysan. It is not a plant normally grown in gardens, so care advice here is limited to general sedge needs.

Family
Cyperaceae (Cyper family)
Grows as
Grass
Light
Full sun
Water
Keep the soil consistently moist to wet, as is typical for coastal sedges.
Soil
Moist, sandy or loamy coastal soil; not commonly sold for potting.
Temperature
Warm tropical conditions; protect below 10 °C.
How easy
Hard
Native range
Hawaiian Is.
Climate
wet tropical

About

Cyperus pennatiformis (formerly Mariscus pennatiformis) is a rare species of sedge known by the common name coastal flatsedge. It is endemic to Hawaii, where it grows on the islands of Maui, Kauai, and Laysan. It is a federally listed endangered species of the United States.

This sedge grows 40 centimeters to 1.2 meters tall with leathery leaves as long as the stem or longer. The flower cluster atop the stem is umbrella-shaped and up to 15 centimeters long by 25 wide. It contains up to 18 spikes which are each made up of several yellowish or grayish spikelets. The spikelet contains up to 25 flowers.

Other Cyperus plants

Cyperus absconditicoronatus · Cyperus acholiensis · Tapertip flatsedge · Cyperus afroalpinus · Cyperus afrodunensis · Cyperus afromontanus · Cyperus afrovaricus · Inflatedscale flatsedge · Cyperus ajax · Cyperus alaticaulis · Cyperus albopilosus · Cyperus albopurpureus

Text excerpted from the Wikipedia article Cyperus pennatiformis by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.

The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.

Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.

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