Quick Facts

Quick facts

• White Spanish Broom (Cytisus multiflorus) is a large shrub with white flowers that is native to south-western Europe.
• It is currently only known with certainty from three sites in central Victoria.
• It is a serious environmental weed of native forest at Creswick, Victoria, having naturalised over about 50 hectares.
• If not eradicated or controlled it has the potential to expand its range much further, threatening to invade a variety of natural ecosystems in the same way as the closely related Cytisus scoparius (Scotch Broom).
• Currently it has not impacted on agriculture or forestry, but the potential for serious impacts is great.
• Control is difficult, and methods similar to the control of Scotch broom can be used.

What Does It Look Like?

What is it?

White Spanish Broom (Cytisus multiflorus) is an erect, deciduous shrub to 4 metres high with numerous stems. The stems are rounded in cross-section, longitudinally ribbed and covered with short silvery hairs when young. Plants are often leafless when in flower. Leaves are arranged in groups of three leaflets on the lower branches and single, stalkless leaflets on the higher branches. The silvery-silky leaflets are linear-lanceolate or narrow-oblong, to 12 mm long and 4 mm wide, with a pointed or blunt and rounded tip.

The pea-like flowers are white with a pink streak at the base and are approximately 8 -12 mm long.

The seed pods (fruit) are covered in short hairs and are linear-oblong, 20-30 mm long and 4-6 mm wide. They turn black at maturity and release seeds explosively when ripe. There are mostly 3-6 ovoid to globose seeds in each pod, each about 2.5 mm long and olive-green to brown in colour (Tutin et al. 1968; Webb et al. 1988; McClintock 1992; Spencer 2002).

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

Flower colour

White

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

In south-western Europe, where White Spanish Broom is native, it grows in the woods, heaths and river banks (Tutin et al. 1968). The Mediterranean climate from where it originates, makes it well adapted to the climate in southern Australia. In the United Kingdom, where it is naturalised in northern Wales and southern England, it grows on banks of roads and railways (Stace 1997). In New Zealand it is naturalised on the North Island, and it grows in dry waste places, scrubland, and riverbeds (Webb et al. 1988).

As a weed, it is known to enter relatively undisturbed bushland. In Australia, it has spread from lakeside plantings into roadsides and townships, but it could also establish in a wide range of disturbed and undisturbed habitats such as grasslands and open eucalypt woodlands (CRC 2003)

White Spanish Broom was first collected from along a watercourse. The current main incursion in Victoria is beside St Georges Lake, with records from the National Herbarium of Victoria noting its original occurrence at this site along the spillway embankment. Contemporary collections in the National Herbarium of Victoria note that it is naturalised in weed invaded Eucalyptus forest on Ordovician deposits (Stajsic 2007, pers. comm.).

Are there similar species?

There are several Cytisus taxa that are available in the nursery trade in south-eastern Australia. Cytisus multiflorus (White Spanish Broom) differs from C. scoparius (Scotch broom) in having the branchlets round in cross-section and longitudinally ribbed, not more or less 5-angled in cross-section as in Scotch broom. Scotch broom usually has three leaflets throughout the plant, compared with three leaflets in the lower branches and a single leaflet in the upper branches in White Spanish Broom.

White Spanish Broom flowers are white, and 8-12 mm long, compared with the flowers of Scotch broom which are longer, usually yellow, partly red or tinged mauve.

Other taxa with which White Spanish Broom can be confused include Cytisus x dallimorei Rolfe (a hybrid between White Spanish Broom and Cytisus scoparius) and Cytisus x praecox Bean. However, C. x dallimorei has three leaflets throughout and pink and crimson flowers while C. x praecox differs from White Spanish Broom in having shortly stalked leaflets (stalkless in white Spanish boom), all the leaves have three leaflets, and the corolla can be white, yellow, pink or red (Spencer 2002).

White Spanish Broom may also be confused with some other genera in the tribe Genistae, the group which is at the centre of taxonomic difficulties in delimiting the genera. One of the genera which may cause confusion in the determination is Retama. Retama differs from White Spanish Broom in producing short inflorescences arising from the main branchlets (axils), with 4-15 flowers on short axes. The pods are hairless (Stajsic 2007, pers. comm.). The pods in Retama are inflated and do not release their seeds explosively unlike both White Spanish Broom and Scotch broom (Jafri & El-Gadi 1980; Cullen et al. 1995).

Why Is It A Weed?

What are its impacts?

White Spanish Broom is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia's ecosystems (CRC 2003).

Agriculture: While its main threat currently is as an environmental weed, reducing native biodiversity and landscape aesthetics, it has the potential to invade pasture and forestry (CRC 2003). Currently there are no reported cases of impact on livestock in Australia. Blood (2001) cites White Spanish Broom as being poisonous. The seeds of the related species Scotch broom are poisonous if ingested in quantity, and the foliage may cause digestive problems in horses (Blood 2001).

Native ecosystems: White Spanish Broom is closely related to Scotch Broom which is an highly invasive species in the cooler, higher rainfall areas of south-eastern Australia and has become widely naturalised in many regions. More than 200 000 hectares of land in eastern Australia has become infested with Scotch broom, and despite attempts to control it, it continues to spread (CRC 2003). White Broom has the same potential to become a highly invasive weed in natural areas of Australia.

How does it spread?

White Spanish Broom is spread mainly by seeds, which are ejected explosively as the pods dry out on warm, sunny days during summer. Most of the seeds fall within 1 metre of the parent plant. They are further dispersed by water (particularly if near streams), mud on machinery (such as road graders, slashers), vehicles and footwear (CRC 2003; Stajsic 2007, pers. comm.). Muyt (2001) cites birds, ants, cattle, horses, animal diggings as being other means of dispersal for the similar species Scotch Broom.

What is its history in Australia?

White Spanish Broom was originally introduced into Australia as a garden ornamental, and it remains commercially available in some nurseries in Australia (CRC 2003).

The earliest collected presumably naturalised specimen was collected in 1933 from Taradale (near Castlemaine), Victoria. It was next collected from a naturalised population at St Georges Lake in Creswick, Victoria in 1963. This remains the main infestation in Victoria. In 2007 self-established plants were collected from a cemetery in Ballarat (National Herbarium of Victoria 2007).

White Spanish Broom has also been reported from the Mount Lofty Ranges in South Australia. The State Herbarium of South Australia herbarium holds four specimens of White Spanish Broom from the Mount Lofty Ranges, collected between 1920-1950, although it is not clear if these are from naturalised plants (Barker 2007, pers. comm.). The Mount Lofty Ranges populations have been eliminated (CRC 2003).

How To Manage It?

Best practice management

Early detection and eradication are crucial. Small infestations can be eradicated if caught early enough. It is highly recommended that any new outbreaks should be reported immediately to your state or territory weed management agency or local council. Do not try to control White Spanish Broom without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem (CRC 2003).

There is relatively little information about the control of White Spanish Broom. Given that it is closely related to Scotch broom, the control methods applied to this species can be used to control or eradicate White Spanish Broom.

Non-chemical control: Manual control: Hand weeding or hoeing is an option for where there are only isolated plants. In smaller incursions the cut and paint method can be applied. Bulldozing and then burning larger infestations of Scotch broom has been used (Parsons & Cuthbertson 1992), but this is best avoided unless there are resources for follow-up management (Muyt, 2001). This is only a partial and temporary solution, as this method creates extensive soil disturbance which favours the germination of soil stored seeds, which will continue to germinate for a number of years. There can be up to 20 000 seeds per square metre in the soil (Sainty et al. 1998). The advantages are that the adult plants are killed, and the seeds are stimulated to germinate, thus quickening the process of waiting for seeds to germinate so they can be destroyed (Cochrane 2001).

Chemical control: Herbicides offer control of broom, especially in preventing spread from small isolated patches (NSW Weedwise 2018), however, there are no registered herbicides for White Spanish Broom (CRC 2003).

For more detailed information on control refer to:

http://www.weeds.crc.org.au/documents/wmg_white_spanish_broom.pdf).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

White Spanish Broom flowers prolifically between September and November but only a small number of the flowers develop into fruit. Pollinators are required for fruit-set to occur (Rodriguez-Riano et al. 2004).

The pods mature during summer, and the seeds are released on warm, sunny days. Autumn and spring rains initiate seed germination. The peak plant growth period is during the spring-autumn period, but growth occurs throughout the year. Plants usually do no produce seed until at least three years of age (CRC 2003).

Where Is It Found?

Which states and territories is it found?

VIC

What areas within states and territories is it found?

The only definitive naturalised records of White Spanish Broom are from central Victoria where it has been recorded from three sites – Taradale near Castlemaine, St Georges Lake at Creswick, and at a cemetery in Ballarat (National Herbarium of Victoria 2007). White Spanish Broom is a serious environmental weed at the St Georges Lake, Creswick area, which is the largest infestation in Australia, over ca. 50 hectares through a Eucalyptus forest.

Where does it originate?

White Spanish Broom is native to south-western Europe: France, Portugal, and Spain. It is also naturalised in Argentina, India, New Zealand, United Kingdom, and western USA (ILDIS 2005; USDA 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

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

Cytisus multiflorus

Other scientific names (synonyms)?

• Cytisus scoparius f. sulphureus (Goldring) Rehder
• Cytisus scoparius var. andreanus (Puiss.) Dippel
• Cytisus scoparius var. prostratus (C.Bailey) F.Hanb. ex A.K.Jacks.
• Cytisus scoparius var. sulphureus Goldring
• Genista andreana Puiss.
• Sarothamnus scoparius (L.) Wimm. ex W.D.J.Koch
• Sarothamnus scoparius var. prostratus C.Bailey
• Spartium scoparium L.

Does it have other known common name(s)?

White Broom, Portuguese Broom