Cyperus polystachyos
bunchy flat-sedge
Australia and warm regions worldwide
Overview
Cyperus polystachyos is a tufted sedge that grows as a short-lived perennial or annual, forming clumps 4-24 inches (10-60 cm) tall. The stems are three-angled and slender, rising from a fibrous-rooted base, with narrow grass-like leaves shorter than the stems. Each stem ends in a dense head of flat, golden-brown to straw-colored spikelets 0.2-0.4 inch (5-10 mm) long, crowded into rounded clusters. Flowering occurs mainly in summer and autumn. After seeding the plant often dies back, and in cooler areas it behaves as an annual. It grows in damp ground, on the margins of wetlands, ditches, and seasonally wet flats. The short lifespan means stands rely on self-seeding to persist.
Native Range
Native to Australia and widespread across tropical and warm-temperate regions worldwide. It grows in damp and seasonally wet ground, including wetland margins, drainage lines, ditches, and the edges of streams and ponds.Suggested Uses
Planted at pond and bog margins, in rain gardens, and in damp revegetation at 8-12 inches (20-30 cm) spacing. It stabilizes the edges of wet ground and drainage lines. The self-seeding habit can spread it beyond the intended area in wet sites.How to Identify
Appearance
Size & Dimensions
Height4" - 2'
Width/Spread6" - 1'
Reaches mature size in approximately 1 years
Bloom Information
Detailed Descriptions
Flower Description
golden-brown to strawFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
It grows in full sun to part shade in wet to moist soils with a pH of 5.5-7.5. It tolerates standing water at the margins and seasonal flooding but declines as soils dry for long periods. In cooler climates it completes its cycle in one season and regrows from seed. Few pests or diseases affect it. Self-sown seedlings appear readily on bare wet ground.Pruning
Cut back spent stems after seeding to keep clumps tidy. Plants regrow from the base where they persist as perennials. Removing seed heads before they ripen reduces self-seeding.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fall
Container Growing
✓ Suitable for container growing
Minimum container size: 3 gallons