Quick Facts

Quick facts

• Cootamundra Wattle (Acacia baileyana) is a native Australian plant that has become an environmental weed in many states of Australia beyond its limited native range.
• It has been extensively planted in gardens and shelter-belts.
• It is a shrub or small tree with silvery grey-green or blue-green bipinnate ("feathery" or "fern-like") leaves and abundant golden yellow, ball-shaped flower heads.
• Reproduction of Cootamundra Wattle is by long-lived seeds, that accumulate in the soil and germinate readily after fire or other kinds of disturbance.
• Control of Cootamundra Wattle requires an integrated, long-term strategy involving manual control, herbicide application and sustained effort to exhaust its soil-stored seedbank.

What Does It Look Like?

What is it?

Cootamundra Wattle (Acacia baileyana) is a shrub or tree that grows to 10 m high with a spreading crown and smooth grey or brown bark on the main stem/trunk and most branches. The branchlets and younger branches have prominent vertical ridges and are covered with a whitish, waxy bloom. They sometimes also bear numerous short soft white hairs. The leaves are bipinnate (finely divided into small leaflets giving the leaves a "feathery" or "fern-like" appearance) and silvery grey-green or blue-green with a whitish bloom.

Flowers occur as ball-shaped golden yellow flower heads that 11-25 flowers. Flower heads are clustered into groups called racemes which are borne on short slender stalks (i.e. peduncles) 4-7 mm long and are alternately arranged on a branch emanating from the forks (i.e. axils) of the leaves, or occasionally at the tip of the stem. Each flower clusters (5-10 cm or more long), contains 8-30 globular flowers, and are significantly longer than the leaves. Flowering generally occurs during late winter and spring, but may occasionally last into early summer in cooler climates  (Weeds of Australia website).

The fruit is an elongated seed-pod (3-10 cm long and 8-15 mm wide) borne on a short stalk. The seed pods are flattened, hairless (i.e. glabrous), and either straight or slightly curved. They are bluish-green in colour and covered in a white powdery substance when young (i.e. pruinose). The pods turn purplish-brown or reddish-brown as they mature. When fully mature the pods split open to release up to 12 dark brown to black seeds. Fruit are normally present during late spring and summer (i.e. from October to January). The seeds (4-7 mm long and 2-4 mm wide) are black, hard-coated, and have a small fleshy structure (i.e. aril) attached to them (Entwisle et al. 1996; Kodela & Tindale 2001; Kodela & Harden 2002; Reid 2008 pers. comm.; Weeds of Australia Website). 

Recognition: Compared to many other bipinnate-leaved wattles, Cootamundra Wattle has silvery-grey twice-compound (i.e. bipinnate) leaves with a few (2-6) pairs of branchlets (i.e. pinnae). These leaves are almost stalkless (i.e. sub-sessile) and the lowermost pair of branchlets (i.e. pinnae) are angled backwards (i.e. reflexed). Its flowers are borne in small globular clusters, with several to many of these clusters being arranged into larger elongated compound clusters (i.e. racemes or panicles). The pods are relatively large (30-120 mm long and 8-15 mm wide) and flattened (Weeds of Australia Website).

For further information and assistance with identification of Cootamundra Wattle contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Tree, Shrub

Where it currently grows? Preferred habitat

In its small native range, Cootamundra Wattle grows in open woodland and mallee communities in stony, undulating or hilly country (Kodela & Tindale 2001; Kodela & Harden 2002). Beyond its native range, it invades woodlands and forests in drier areas where annual rainfall exceeds 400 mm (Muyt 2001).

Are there similar species?

Cootamundra Wattle is generally similar to other bipinnate wattles. However, the silvery grey-green or blue-green leaves should separate it from most similar species. It can be distinguished from Silver Wattle (Acacia dealbata), a widespread wattle with similar-coloured foliage, by its relatively short leaves with usually only 2-4 (sometimes up to 6) pairs of leaflets. Silver Wattle has longer leaves with up to 20 (sometimes more) pairs of leaflets (Entwisle et al. 1996; Kodela & Tindale 2001; Kodela & Harden 2002). The formation of hybrids, with other bipinnate wattles (including Silver Wattle), that are intermediate in appearance will make identification more difficult. It is important to locate and recognise the likely parent species (Reid 2008 pers. comm.).

Why Is It A Weed?

What are its impacts?

Native ecosystems:  In many places beyond its native range, Cootamundra Wattle is an environmental weed that competes with native shrubs, small trees and ground flora, and impedes their regeneration (Blood 2001; Muyt 2001; Reid 2008 pers. comm.). It is a very serious threat to heathland and heathy woodland, lowland grassland and grassy woodland, dry sclerophyll forest and woodland, and riparian vegetation (Carr et al. 1992). Cootamundra Wattle is reported to hybridise with at least six other Australian wattles thereby threatening the integrity of native wattle populations through genetic pollution. Two of the species it is known to hybridise with, Early Black Wattle (Acacia decurrens) and Silver Wattle (Acacia dealbata), are also environmental weeds outside their native ranges. This adds complexity to its potential impact on native vegetation and to weed control efforts (Kodela & Tindale 2001, Reid 2008 pers. comm.).

How does it spread?

Cootamundra Wattle has been extensively planted in gardens and shelter-belts. It is still widely available in nurseries, garden centres, fetes and markets (Blood 2001). The hard, long-lived seeds are spread by birds and ants, on machinery and in garden waste (Muyt 2001).

What is its history in Australia?

Cootamundra Wattle is an Australian native plant and was introduced into Australian horticulture in the late 1800s or early 1900s. It does not appear in nursery catalogues in Victoria until 1889 (Brookes & Barley 1992), however, it is presumed to be well known in cultivation soon after this time. The New South Wales branch of the Wattle Day League celebrated Wattle Day in 1913 by planting 200 wattle trees in Centennial Park, Sydney, including a grove of Cootamundra Wattle (Anon. undated).

How To Manage It?

Best practice management

An integrated, long-term strategy is needed to eliminate infestations of Cootamundra Wattle. Several years are required to exhaust its soil-stored seed bank and prevent more seeds being added to it.

Physical control: Seedlings of Cootamundra Wattle can be hand-pulled and small plants dug out. Older mature plants do not usually re-shoot, so they can be ring-barked or cut down without herbicide application. Fire destroys plants and stimulates seed germination, enabling the resulting seedlings to be manually removed or sprayed. Follow up treatments will be required for several years (Muyt 2001). Because the seeds of Cootamundra Wattle are bird spread, treat plants before they fruit. Bag and remove all pods (Weeds of the Blue Mountains website).

Chemical control: A range of herbicide treatments can also be used. Younger plants can be treated by cutting stems back to near ground level and painting the cut stem with a suitable herbicide (the cut-paint method) or by injecting a suitable herbicide into drill holes at the base of the plant (the drill-fill method). Seedlings and smaller plants can be sprayed with selective and non-selective herbicides.

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

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Cootamundra Wattle plants begin to flower when they are two years old (Morgan et al. 2002). Flowers are produced between June and September, but individual plants only flower for a few weeks. Pods mature between October and January (Kodela & Tindale 2001; World Wide Wattle undated a).

Important factors contributing to the weediness of Cootamundra Wattle are its ability to produce high numbers of flowers and seeds. It is also able to do this in plants as young as two years old (Morgan et al. 2002). The hard seeds can remain viable in the soil-stored seed bank for more than ten years. This creates the potential for mass germination in the event of fire or soil disturbance (Muyt 2001, World Wide Wattle undated b).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, VIC, SA, WA

What areas within states and territories is it found?

Cootamundra Wattle has been extensively planted outside its limited natural range.  It is now naturalised in south-eastern Queensland, south-western Western Australia, and south-eastern South Australia (mainly in the Northern and Southern Lofty regions near Adelaide and on the Yorke Peninsula) and the ACT. It is most widespread in Victoria, particularly in the central and western parts of the state. It has also become naturalised in many parts of New South Wales beyond its native range, particularly in coastal districts and on the central and southern tablelands. It has also been reported as a weed in Tasmania, however this has not been confirmed by herbarium records (Weeds of Australia website).

Cootamundra Wattle has also become naturalised in other parts of the world, including southern Africa, New Zealand and south-western USA (i.e. California) (Weeds of Australia website).

Where does it originate?

Cootamundra Wattle is an Australian native plant with a very restricted natural distribution. It is native only in the Cootamundra, Stockinbingal and Temora district within the Western Slopes region of New South Wales (Kodela & Tindale 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT

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

Acacia baileyana

Other scientific names (synonyms)?

• Acacia baileyana var. aurea Pescott
• Acacia baileyana F.Muell. var. baileyana
• Racosperma baileyanum (F. Muell.) Pedley

Does it have other known common name(s)?

Golden Mimosa