Broom Rush
Botanical name: Juncus sarophorus
Synonyms: Agathryon sarophorum
Common name(s): Broom rush, Fan-flowered rush

About:
A robust indigenous perennial rush forming dense, strongly tufted tussocks of distinctive dull blue-green stems. The stems are tightly clustered and upright near the base but characteristically arch or droop outward through their upper half, producing a broad, fountain-like mature plant.

One of its most useful identification features is the compact, many-flowered, fan-shaped inflorescence. The numerous flowering branches are pressed closely against the long subtending bract, giving the flower head a flattened, broom- or fan-like appearance.

Juncus sarophorus is indigenous to both New Zealand and Australia and is widespread through much of New Zealand. Although valuable in natural wetlands and restoration plantings, its vigorous growth means it can occasionally become a troublesome pasture weed.

Natural habitat:
Coastal to lowland.

Naturally occurs in damp, open ground, particularly wet pasture, coastal wetland margins, swampy depressions, river flats, riparian areas and other periodically saturated sites.

It favours open habitats with abundant light and is well adapted to sites experiencing fluctuating moisture levels.

Growing environment:
Full Sun, Partial Shade, Damp Soil, Wet Soil, Heavy Soil, Coastal Exposure, Frost & Wind tolerant.

Best growth occurs in open, consistently moist ground, although established plants can tolerate periods of considerably drier conditions.

It is a hardy species capable of growing in exposed environments and disturbed wet ground.

Endemic distribution:
Indigenous but not endemic to New Zealand.

Occurs in the North Island, South Island, Stewart Island/Rakiura, Chatham Islands and Campbell Island/Motu Ihupuku.

Also indigenous to Australia.

Height:
1–2 m.

Width:
Approximately 1–1.5 m when mature, depending on growing conditions.

Flowering:
September–January.

The apparently lateral inflorescence is usually about 2–18 cm long and may reach approximately 6 cm wide.

Numerous very small flowers are densely arranged along stiff, slender branchlets. These branchlets are held closely against the long subtending bract, producing the characteristic fan-shaped flower head.

Flowers are approximately 2 mm long. The tepals are initially white and membranous with a central green stripe, becoming straw-coloured and more rigid with age.

Fruiting:
October–May.

Produces narrow ovate-oblong capsules approximately 1.5–2 mm long, generally equal to or only slightly longer than the tepals.

Mature capsules are characteristically very pale brown.

Uses:
• Wetland restoration
• Riparian revegetation
• River-flat restoration
• Stormwater plantings
• Pond and waterway margins
• Coastal wetland restoration
• Bank and soil stabilisation
• Erosion control
• Wildlife habitat
• Naturalistic wet gardens
• Mass native plantings

Its dense growth and tolerance of wet ground make it particularly useful where a tall, robust native rush is required.

Appearance:
Growth habit:
A densely tufted, tussock-forming perennial arising from a stout horizontal rhizome approximately 5–10 mm in diameter.

Numerous stems are packed tightly together and remain erect around the base before characteristically bending and drooping outward through their upper half or third.

This creates a dense base with a softer, spreading upper canopy.

Leaves:
True leaves are absent.

The basal sheathing bracts are distinctive, typically black at the very base and otherwise dark reddish-purple. They tightly sheath the stems.

The uppermost bract is generally straw-coloured and can reach approximately 25 cm long.

The photosynthetic flowering stems are approximately 1–2 m tall and 2–3 mm in diameter. They are dull blue-green, ridged, wiry and non-glossy.

Internally, the pith is characteristically cobweb-like and irregularly interrupted by large cavities, although it is rarely continuous.

Flowers:
The many-flowered inflorescence is one of the species’ most distinctive features.

Numerous stiff, erect to spreading branchlets carry closely spaced flowers and are pressed tightly against the long subtending floral bract. Together they form a dense, flattened fan-like arrangement.

The subtending bract extends beyond the flowers and may reach approximately 30 cm long.

Flowers are approximately 2 mm long with six tepals. These are initially pale, membranous and green-striped before becoming straw-coloured.

Usually three stamens are present, although occasionally up to six occur.

Fruit:
The capsules are approximately 1.5–2 mm long, narrow and ovate-oblong with an obtuse apex.

They are approximately equal to or slightly longer than the surrounding tepals and mature to a very pale brown.

Seeds develop a mucilaginous coating and are capable of dispersal by water, wind and attachment to animals.

Ecology:
Juncus sarophorus is an important structural species of open damp ground and wetland margins.

Its dense tussocks provide low-level cover and habitat for wetland invertebrates and other fauna, while its rhizomatous root system helps bind wet soils and stabilise disturbed ground.

The species readily occupies open and disturbed sites, including pasture and river flats. This adaptability makes it useful for revegetation but also means it can spread vigorously into agricultural land.

Its wetland indicator classification is Facultative Wetland (FACW), meaning it usually occurs as a wetland plant but can occasionally establish in non-wetland environments.

Associated habitats:
Coastal wetlands, freshwater wetlands, swamp margins, damp pasture, river flats, riparian margins, drainage areas, wet hollows, seasonally inundated ground and open lowland vegetation.

It may occur alongside other native rushes and sedges as well as flax (Phormium tenax) and other moisture-loving wetland vegetation.

How to grow:
Plant in full sun to partial shade in damp or wet soil.

It performs particularly well around ponds, drainage channels, wetlands and riparian margins, but established plants are capable of tolerating temporary dry periods.

The species is hardy and requires little maintenance once established. Its eventual size and vigorous growth should, however, be considered carefully when selecting a planting site.

Avoid planting immediately beside productive pasture or small garden beds where unwanted spread could become difficult to manage.

Propagation:
Easy to propagate from fresh seed.

Sow seed onto a consistently moist seed-raising medium and maintain high moisture levels while seedlings establish.

Established plants can also be divided. Lift a mature tussock and separate it into smaller rooted sections, ensuring each division retains healthy rhizome and active shoots.

Replant immediately into moist ground and water thoroughly until established.

Cultural use:
No specific traditional Māori use is well documented for Juncus sarophorus itself.

Rushes collectively were important plants for fibre, binding and other practical purposes, reflected in the derivation of the genus name Juncus from the Latin jungere, meaning “to join, tie or bind”.

However, such general historical uses should not automatically be attributed specifically to Juncus sarophorus without supporting evidence.

Garden value:
A hardy and strongly architectural native rush particularly suited to larger gardens, wetland landscapes and naturalistic plantings.

Its dense blue-green tussocks and outward-drooping stems create a graceful fountain-like form, while the unusual fan-shaped flower heads provide additional botanical interest.

It is especially valuable around ponds, streams, rain gardens and larger wet areas where a substantial native rush is required.

Because plants can reach around 2 m tall and spread considerably, Juncus sarophorus is better suited to larger landscapes than small garden beds. Its ability to spread readily should also be considered when planting near pasture or intensively managed areas.