Quick Facts

Quick facts

• Spiny Broom (Calicotome spinosa) is a native of the Mediterranean region that was introduced to Australia as an ornamental or hedge plant.
• It is a spiny shrub growing up to 3m high with yellow pea flowers.
• Dense patches of Spiny Broom reduce the area available for grazing, limit stock access to watering points and provide refuge for pest animals.
• The movement of seed in soil by earth-moving machinery is one of the major ways this weed is spread.
• Effective control of Spiny Broom requires a strategic program integrating a range of techniques including manual removal, burning and, where necessary, chemical applications.

What Does It Look Like?

What is it?

Spiny Broom (Calicotome spinosa) is a spiny shrub growing up to 3 m high. The branches are hairless and finely ribbed lengthwise with stiff, spine-tipped side branches that are 10-40 mm long and bear most of the leaves and flowers. The leaves are divided into three leaflets (segments of a leaf). The leaflets are more or less oval in shape, 5-10 mm long, 2-5 mm wide, hairless above and sparsely hairy below.

Yellow pea flowers, 12-15 mm long, are borne along short side branches in clusters of one to five.

Fruit takes the form of mature seed pods which are dark brown, hairless, 30-45 mm long and 5-7 mm wide with a distinctive narrow flange (wing) along one edge and a short (1-2 mm) pointed tip. The seeds are smooth, shiny, yellowish brown, about 3.5 mm long and 2 mm wide (Webb et al. 1988; Jeanes 1996; Reid 2008 pers. comm.).

For further information and assistance with identification of Spiny Broom, contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

Spiny Broom prefers slightly acid, dry, rocky soils in areas with moderate rainfall (Parsons & Cuthbertson 2001). Most naturalised records come from weedy roadsides and adjoining farmland (National Herbarium of Victoria 2008).

Are there similar species?

Spiny Broom is similar in appearance to other shrubs that have yellow pea flowers and leaves divided into three leaflets. These include weedy and/or introduced Genista and Cytisus species. The stiff, spine-tipped side branches (10-40 mm long) of Spiny Broom should readily distinguish it from these species (Reid 2008 pers. obs.).

Camel Thorn (Alhagi maurorum) is a smaller shrub, also with spine-tipped side branches, but these are finer and a greyer green than Spiny Broom. The flowers of Camel Thorn are mainly red and purple rather than plain yellow as in Spiny Broom (Jeanes 1996; Parsons & Cuthbertson 2001; Reid 2008 pers. obs.).

Gorse (Ulex europaeus) is also a spiny shrub with yellow pea flowers. It differs from Spiny Broom in having spines more densely distributed along the main branches, no leaves on mature plants and relatively short (10-20 mm) densely hairy pods (Jeanes 1996; Muyt 2001; Reid 2008 pers. obs.).

For further information and assistance with identification of Spiny Broom, contact the herbarium in your state or territory.

Why Is It A Weed?

What are its impacts?

Agriculture: Dense patches of Spiny Broom reduce the area available for grazing, limit stock access to watering points and provide refuge for pest animals. Animals are able to graze young shoots but do not eat older plants because of the spines. Young plants are claimed to be toxic but evidence is lacking (Parsons & Cuthbertson 2001). Spiny Broom is rated a serious threat to native vegetation in lowland grassland, grassy woodland and dry sclerophyll forest in Victoria (Carr et al. 1992).

How does it spread?

The seeds of Spiny Broom are ejected explosively from the pods. They are further dispersed by animals and water, by the movement of soil and mud on road graders and earth-moving equipment and from dumped garden refuse (Blood 2001; Parsons & Cuthbertson 2001).

What is its history in Australia?

Spiny Broom was probably introduced to Australia as an ornamental or hedge plant. The earliest record of its availability in cultivation in Victoria is under the name Cytisus spinosus, listed in a nursery catalogue published in 1864. It is also recorded, again under the name Cytisus spinosus, as growing in the Royal Society's Gardens in Hobart, Tasmania in 1865. The first apparently naturalised record was in 1909 from Ballarat where it was noted as growing along roads (Brookes & Barley 1992; Parsons & Cuthbertson 2001; National Herbarium of Victoria 2008).

How To Manage It?

Best practice management

A long-term strategic program is required to effectively control Spiny Broom, concentrating on exhausting the seed bank and preventing further additions to it. New infestations should be treated before plants reach the flowering stage. Once plants start to produce seeds, control becomes more difficult and dispersal to other areas is likely. Soil disturbance and fire will stimulate germination of seed in the soil and further treatment over two or three years will be needed to kill the resulting seedlings (Muyt 2001).

Chemical control: Where chemical control is needed a suitable herbicide can be applied to actively growing plants in full leaf before flowering (Parsons & Cuthbertson 2001).

For chemical information, see the Australian Pesticides and Veterinary Medicines Authority, available at http://www.apvma.gov.au 

Non-chemical control: Seedlings and smaller plants can be dug out (Muyt 2001). Larger plants or plants in clumps can be grubbed out with a bulldozer or tractor and chain, taking care to remove most of the rootstock because it can resprout. Grubbed clumps can be ploughed to bring roots to the surface so they can be burned (Parsons & Cuthbertson 2001).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Seeds of Spiny Broom are long lived, and germinate mostly in autumn. Plants rarely flower before two to three years of age. Flowers are produced from November to January and seeds are shed in early summer (Blood 2001; Parsons & Cuthbertson 2001; National Herbarium of Victoria 2008).

Where Is It Found?

Which states and territories is it found?

VIC

What areas within states and territories is it found?

All Australian naturalised records of Spiny Broom are from Victoria where it has a scattered occurrence to the west, east and south-east of Melbourne (Parsons & Cuthbertson 2001; National Herbarium of Victoria 2008). There is a 1964 collection from Red Hill east of Perth, Western Australia, but Spiny Broom is not considered to be naturalised in that state (Western Australian Herbarium 1998; Parker pers. comm. 2008).

Where does it originate?

Spiny Broom is native to the Mediterranean region (Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

VIC, WA

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

Calicotome spinosa

Other scientific names (synonyms)?

Spartium spinosum L.

Does it have other known common name(s)?

Spiny Broom