Quick Facts

Quick facts

• Originally from Mediterranean region, Flax-leaf Broom (Genista linifolia), a Weed of National Significance, is a yellow flowered shrub, 3 m tall, highly invasive with serious impacts on the environment, agriculture and the economy in southern Australia.
• Invades native woodlands to grasslands, in temperate areas and out-competes other vegetation by shading and nitrogen fixation.
• In agricultural situations it can form dense stands which reduce grazing and provide habitat for pest animals.
• Spread by seed, mature healthy plants form dense thickets that can produce many seeds per year forming a large long-lived seed-bank.
• The movement of soil-stored seed by earth-moving machinery is a major way this weed is spread with early detection and good hygiene within infestations preventing spread.
• Control is difficult, with effective control requiring a strategic program integrating a range of techniques including manual removal, burning and chemical applications, and biological control.
• All control programs should aim to reduce the amount of seed produced, with prevention the most cost-effective form of weed control.
• Tackle the small, outlying infestations before they set seed. This results in less follow-up where the seed-bank will be small.

What Does It Look Like?

What is it?

Flax-leaf Broom (Genista linifolia) is an evergreen perennial, erect or spreading shrub to 3 m high. The stems are ribbed and covered with many short adpressed soft hairs (pressed close to or lying flat against stem). The leaves are almost stalkless and divided into three narrow leaflets. Each leaflet is 10-25 mm long, 1-4 mm wide, more or less straight-sided with margins rolled under, with a short point at the tip. They are dark green and sparsely hairy on the upper surface and much paler with a dense covering of hairs on the lower surface.

The yellow pea flowers are 10-15 mm long and more or less clustered in groups of 3-16 at the ends of short branchlets. Larger lower flowering petal silky-haired. Flowering is mainly between August and November.

Mature fruits (pods) are narrow brown, 10-30 mm long and about 5 mm wide and with a dense covering of shaggy hairs with each pod containing 2-6 seeds. The hard seeds are olive-green in colour and 2-3 mm across (Jeanes 1996; Muyt 2001; Parsons & Cuthbertson 1992).

Recognition: This species can normally be recognised by the combination of the following characters; Silvery bush from a distance; young stems are ridged, green and lightly hairy; leaves are stalkless (or on a short leaf stalk), are trifoliate (have three-leaflets), leaflets thin and straight-sided with margins rolled in, each ends in a short point; flowers are yellow and pea-like, 10–15 mm long in clusters of 3 to 16; fruits (pods) are hairy all over, brown to black in colour when ripe, 10–15 mm long and 2-3 mm wide. with 2-6 seeds; seeds are olive-green in colour and 2-3 mm across.

Flower colour

Yellow

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

In the Mediterranean region where it is native, Flax-leaf Broom grows in woodland and scrub, and has a preference for acidic soils (Tutin et al. 1968). Like Montpellier broom flax-leaf Broom can inhabit a broader range of habitats than Scotch broom because it tolerates warmer and drier Mediterranean climates (Office of Environment and Heritage 2014)

It invades a variety of different native ecosystems, such as woodlands and open areas including dunes and coastal areas, usually favouring disturbed sites, such as roadsides, and railway embankments, in regions with a warm temperate climate, moderate rainfall, and slightly acidic soil (Parsons & Cuthbertson 1992; Csurhes & Edwards 1998). It tolerates both relatively dry and wetter sites (Stajsic 2007, pers. comm.).

Are there similar species?

Flax-leaf Broom (Genista linifolia) is generally similar to other shrubs that have yellow pea flowers and leaves divided into three leaflets. These include some native plants could be mistaken for Broom species including;  Goodia species example; Goodia lotifolia, indigenous to the east coast of Australia (Muyt 2001); Bossiaea foliosa; Exocarpus species, for example Exocarpus strictus; Jacksonia scoparia; Pultenaea daphnoides (large-leaf bitter-pea); and Viminaria juncea (native broom or swiftbush).

Other weedy species that could be mistaken for Cape Broom including the introduced Genista and Cytisus species.

Flax-leaf Broom (Genista linifolia) differs from both Cape Broom (Genista monspessulana) and Madeira Broom (Genista stenopetala) in having almost stalkless or very shortly stalked leaves (note that the individual leaflets are shortly stalked), which are linear or narrowly elliptic linear-oblanceolate. The leaflets on Cape Broom are egg-shaped, and those on Madeira Broom are elliptic or egg-shaped (Webb et al. 1988; Jeanes 1996; Stajsic 2007, pers. comm.). Flax-leaf Broom has its flowers arranged in short dense clusters at the ends of the branches. Those of Cape Broom are borne singly or are arranged in small clusters on short branches along the stems.

Dyers Broom (Genista tinctoria) differs in having leaves with a single leaflet only (Jeanes 1996).

The flowers of Madeira Broom are arranged in elongated clusters at the ends of the branches (Navie 2004).

English Broom (Cytisus scoparius) is an erect shrub of a similar size, with larger yellow pea-like flowers and smooth, (without hairs on the) stems and leaves. The young stems are deep green, five-sided or angled. Plants also have longer pods (fruits) to 70 mm long.

Gorse (Ulex europaeus) is a very spiny shrub, of similar size, also with yellow pea-like flowers.

Why Is It A Weed?

What are its impacts?

Flax-leaf Broom (Genista linifolia) is a Weed of National Significance (WoNS), is regarded as an environmental weed, and is seen as posing a very high threat to numerous native vegetation communities as well as being a problem for agriculture (Carr et al. 1992; Parsons & Cuthbertson 1992; Csurhes & Edwards 1998).

Agriculture: Flax-leaf Broom is believed to be toxic but is rarely grazed and as such isn't perceived as being a problem. However, it can from dense clumps which reduce grazing area (Parsons & Cuthbertson 1992).

Native ecosystems:  The dense clumps and hedge rows formed by Flax-leaf Broom exclude native vegetation and can provide habitat for feral animals (Parsons & Cuthbertson 1992; Csurhes & Edwards 1998). It out-competes native plants by using nitrogen fixation to increase soil fertility. Furthermore, Flax-leaf Broom is also considered a serious fire hazard (Office of Environment and Heritage 2014) and is able to recover quickly after disturbances such as fire (Australian Weeds Committee 2011).  It is a weed of disturbed areas such as roadsides but it also invade a range of woodland and forest types, damp sclerophyll forest, grassy woodland, lowland grassland, coastal shrubland, and riparian vegetation, (Carr et al. 1992). Flax-leaf Broom readily colonises coastal areas and in southern Australia it invades sand dunes (Office of Environment and Heritage 2014).

Urban areas: Readily invades disturbed areas such as roadsides, rail embankments, fence-lines, and abandoned grazing paddocks or uncared for land.

How does it spread?

Flax-leaf Broom is spread solely by seeds, which are ejected explosively as the pods dry out on warm, sunny days during summer. Most of the seeds are most likely to fall within a few metres of the parent plant. They may be further dispersed by water if near streams, mud on machinery (such as road graders, slashers), vehicles and footwear (Parsons & Cuthbertson 1992; Muyt 2001). Birds, ants and stock, as well as the dumping of seed-bearing garden refuse are other means of dispersal for Genista species in general (Muyt 2001).

What is its history in Australia?

Flax-leaf Broom (Genista linifolia) was probably introduced into Australia as an ornamental garden plant. It was cultivated at the Adelaide Botanic Gardens in 1858 and in Victoria in 1855 (Parsons & Cuthbertson 1992). In Victoria the earliest collection is from 1885 from Talbot, but it is unknown if it was naturalised or collected from a cultivated plant. The earliest known collection of a naturalised plant in Victoria is a 1912 specimen from Pakenham with the notes "now naturalized, and spreading rapidly in the Pakenham district" (National Herbarium of Victoria 2007). The earliest collections from South Australia and Western Australia are much later (1952 and 1967 respectively) (eFlora SA 2001; Western Australian Herbarium 1998–).

How To Manage It?

Best practice management

Given that Flax-leaf Broom (Genista linifolia) is possible by chemical, mechanical, and biological means.  As flax-leaf Broom is closely related to the genus Cytisus, the control methods applied for Cytisus scoparius, C. multiflorus, and Cape Broom (Genista monspessulana) can be used to control or eradicate Genista linifolia (Muyt 2001).

It is very important to control isolated young plants should be controlled before they set seed to prevent the establishment of a soil seed bank (Australian Weeds Committee 2011). Because of the longevity of the soil-stored seeds of Flax-leaf Broom and other Genista species, which can remain dormant for at ten years (or more), eliminating larger infestations should be approached as a long-term endeavour (Muyt 2001).

Seeds of Genista species usually fail to establish in dense shade. As such creating any soil disturbance will normally induce a mass germination of soil stored seeds, which may continue to germinate for a number of years. In established infestations of Genista, seed numbers can reach several thousand per square metre (Muyt 2001).

Chemical control: Various herbicide are effective and available for use, please see, Office of Environment and Heritage (2014)  and DPI NSW (2019) for further details. Herbicide application methods are:

Foliar spraying: Foliar herbicide spraying is the application of herbicide solution to weed foliage in the form of a spray, a common method used for woody plants. Foliar herbicide spray can be applied to control Flax-leaf Broom, but follow-up treatments of re-growth of mature plants are necessary. Smaller plants can be slashed to control their regeneration and any regrowth sprayed with a suitable herbicide. Furthermore, damage to native plants should be minimised Australian Weeds Committee 2011).

Cut-and-swab method (Cut stump treatment): is when each stem is cut off at ground level and immediately applying herbicide to the cut surface killing the plant to prevent regeneration from the rootstock.

Basal barking: Herbicide can be applied to the bark of smaller stems. This method involves applying herbicide mixed with an adjuant to the lower trunk or stem of woody plants up to around 50 mm in diameter to a height of 30-40 cm above ground level.

Stem injection (drill-and-fill): Herbicide can be injected into the bark of larger stems (Australian Weeds Committee 2011). Stem injection delivers herbicide directly to the sapwood but is rarely used on brooms, but when used, it is for plants with stems over 50 mm in circumference.

Scrape-and-paint: This method involves scraping away a small section of the bark and applying herbicide directly onto the sapwood. It is an effective but rarely used technique normally used on larger plants.

Splatter or gas gun:  splatter guns were developed over thirty five years ago for sheep drenching and has been adapted for weed spraying using chemicals.

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au.

NOTE: Training is normally a requirement in most States and Territories for all or some of the methods.

Non-chemical control: Control methods are described in detail in Office of Environment and Heritage (2014). Non-chemical methods are usually followed up with chemical (herbicide) applications. 

Physical control:  Seedlings and smaller plants can be dug out with small tools, or pulled out by hand, preferably when the ground is moist and soft. Hand weeding or hoeing is an option for where there are only isolated plants. This is normally used in new infestations that have not flowered or in area after mature plants have been removed, and this type follow-up removes the many new seedlings that would have subsequently germinated. Older senescent broom plants can be cut at or below ground level, sometimes without the subsequent use of herbicide as they usually do not re-sprout or coppice at that stage of their life cycle.

Mechanical control: Bulldozing and then burning has been used for larger infestations of Cytisus scoparius (Parsons & Cuthbertson 1992). Removal by clearing is a useful method of controlling large infestations of Cape Broom. Crushing, mechanical pulling plants, or slashing with machinery clears areas ready for follow-up control methods required when mass of germination of Cape Broom seedlings will occurs from the soil seed-bank.

Mulching: Mulching or grooming with a tractor or excavator-mounted mulcher cuts bushes off at ground level and processes them to fine mulch. The mulch provides some suppression of seedling growth leaving a cleaner site after control than some other mechanical methods.

Cultivation: Cultivation with disc or mouldboard ploughs is useful for breaking established roots and for follow-up treatment of seedlings and regrowth in large infestations.

Competition and management: Stock availability, adequate fencing and the establishment of strong pasture grasses are the keys to using grazing to improve broom management.

Fire:  Most adult plants are killed by fire, but some are capable of re-sprouting from the rootstock. Although the amount of soil-stored seed may be reduced by burning, effective control can only be achieved by regular treatment of regenerating seedlings by hand-pulling or herbicide application for 3 to 5 years following fire (Muyt 2001; Department of Primary Industries Victoria 2004, Australian Weeds Committee 2011). Soil-stored seed is stimulated to germinate following fire and may continue to germinate for many years following burning.

Biological control:  Flax-leaf Broom has also been recognised as a target for biological control through a cross-jurisdictional government process. This allows activities to be undertaken to develop effective biological controls. However, no biological control program has yet been initiated (Australian Weeds Committee 2011).

For more detailed information on control refer to Parsons & Cuthbertson (1992), Cochrane (2001) and Muyt (2001), Office of Environment and Heritage (2014) and DPI NSW (2019).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Flax-leaf Broom flowers mainly between August and November (Marchant et al. 1987; Jeanes 1996). Plants do not produce flowers until they are at least two years old. Most of the growing period of Genista species in southeastern Australia occurs during the warmer months. Seeds are shed in spring and summer, and they germinate in autumn and spring (Parsons & Cuthbertson 1992).

Where Is It Found?

Which states and territories is it found?

NSW, QLD, SA, TAS, VIC, WA

What areas within states and territories is it found?

Flax-leaf Broom (Genista linifolia) is naturalised in Western Australia, South Australia, New South Wales, Victoria, and a small number of collections from Tasmania.

In New South Wales it has naturalised in the Central Coast, Central Tablelands, South West Slopes, and South West Plains regions (PlantNet 2007). In New South Wales it has been observed mainly as a weed of disturbed areas such as roadsides but it also occurs in Eucalyptus woodland as at Hazelbrook in the Blue Mountains (Harden 2002; National Herbarium of Victoria 2007).

In Queensland it is doubtfully naturalised.

In South Australia it has been collected from the Eyre Peninsula, the Northern and the Southern Lofty regions (eFlora SA 2020).

In Tasmania it only occurs at a few localities.

In Victoria it has been collected predominantly south of the Great Dividing Range, from the Grampians, Bellarine Peninsula, to Avoca in central Victoria, and most collections being from east and southeast of Melbourne (National Herbarium of Victoria 2007). It has invaded a range of woodland and forest types. At Moe it grows in Eucalyptus obliqua woodland and at Fraser National Park it is common in box woodland (National Herbarium of Victoria 2007). At Port Arlington it is a weed of coastal Acacia shrubland and at Anglesea it is roadside weed adjacent to coastal woody heathland. It also invades lowland grassland and grassy woodland, damp sclerophyll forest, and riparian vegetation (Carr et al. 1992).

In Western Australia it occurs predominantly between Perth and Busselton, and near Albany. It not only invades disturbed roadsides, but has also been collected as a riparian weed in Eucalyptus rudis woodland, at York. At Mt Barker it was noted as growing in Melaleuca preissiana and Agonis association, and at Bindoon it was collected in Eucalyptus wandoo woodland (Western Australian Herbarium 1998–). 

Where does it originate?

Flax-leaf Broom (Genista linifolia) is native to the western Mediterranean region of Europe (Tutin et al. 1968), including France (south and Corsica), Spain (including Baleares and Canary Islands), as well as in Algeria and Morocco (GRIN 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

YES

Where is it a declared weed?

ACT, NSW, VIC

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Genista linifolia

Other scientific names (synonyms)?

• Cytisus linifolius (L.) Lam.
• Teline linifolia (L.) Webb & Berthel.

Does it have other known common name(s)?

Flax-leaved Broom, Flax Broom.