Quick Facts

Quick facts

• Narrow Leaf Cotton Bush (Gomphocarpus fruticosus) is an upright perennial plant that normally has a rather slender shrubby habit and grows 0.5 to 2 m tall.
• It has milky sap and produces distinctive balloon-shaped fruit that are covered in soft spines.
• It is widely naturalised in southern Australia, but is most common and widespread in eastern New South Wales and south-western Western Australia.
• Narrow Leaf Cotton Bush is poisonous to livestock and humans and dense infestations can substantially reduce the productivity of pastures.
• It is also a common weed of grasslands, open woodlands and riparian areas, where it can form dense thickets that compete with and replace native plants.

What Does It Look Like?

What is it?

Narrow Leaf Cotton Bush (Gomphocarpus fruticosus) is an upright perennial plant that normally has a rather slender shrubby habit and grows 0.5 to 2 m tall. Its stems are pale green in colour and covered in small whitish hairs when young. These stems turn brown in colour and become somewhat woody with age. All parts of the plant, and particularly the stems, exude a milky sap when broken or damaged. The leaves are narrow or very elongated in shape (4 to 12.5 cm long and 5 to 15 mm wide) and taper to a point at both ends. They are oppositely arranged along the stems and are borne on short stalks 3-10 mm long. Their upper surfaces are usually shiny and pale green, while their lower surfaces are paler and duller in appearance (Navie & Adkins 2007).

The flowers are borne in loose, drooping clusters in the forks of the upper leaves. These clusters consist of 3-10 flowers, each flower being borne on a slender stalk (10 to 20 mm long), and the flower stalks all radiating from the same point. The flowers (about 2 cm long and 12 to 13 mm across) are white or cream coloured (sometimes with a slightly pinkish tinge) and are slightly tubular in appearance. They have five waxy petals that are fused together at the base with hairy lobes 6 to 7 mm long. In the centre of these flowers are five pouch-like projections that form a distinctive crown-like structure (a corona). The flowers also have five small and narrow sepals and five stamens.

The distinctive fruit are balloon-like or bladdery in appearance (4 to 7 cm long and 1.5 to 3.5 cm wide) and light green in colour. They are borne on an S-shaped stalk, are slightly curved and gradually taper to a short projection (a beak) at their tips. These fruit are covered in soft spines up to 10 mm long and split open at maturity to release their numerous seeds. The seeds (about 6 mm long and 3 mm wide) are brown or black in colour, flattened, and topped with a tuft of numerous white silky hairs about 30 mm long (Navie & Adkins 2007).

For further information and assistance with identification of Narrow Leaf Cotton Bush contact the herbarium in your state or territory.

Flower colour

White

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

Narrow Leaf Cotton Bush grows in a wide range of environments including warm temperate, sub-tropical, tropical and occasionally even semi-arid regions. It is a weed of roadsides, disturbed sites, waste areas, waterways, pastures, open woodlands and fallows (Navie & Adkins 2007).

Are there similar species?

Narrow Leaf Cotton Bush is very similar to Balloon Cotton Bush (Gomphocarpus physocarpus). These two species often grow together and readily hybridise, eventually producing hybrid swarms. These hybrid swarms consist of plants that gradually intergrade between to two species, sometimes making it impossible to assign individual plants to a particular species (Navie & Adkins 2007).

However, typical Narrow Leaf Cotton Bush plants have narrowly egg-shaped and slightly curved fruit that gradually taper to a short pointed projection. On the other hand, Balloon Cotton Bush fruit are almost round in shape and come to an abrupt point, often with a sunken tip (Navie & Adkins 2007).

Why Is It A Weed?

What are its impacts?

Narrow Leaf Cotton Bush was included in the list of 71 species that were nominated by state and territory governments for assessment as Weeds of National Significance (WONS). Following an assessment process, Narrow Leaf Cotton Bush was not included as one of the 20 WONS. However, it remains a weed of potential national significance.

Dense infestations of Narrow Leaf Cotton Bush can substantially reduce the productivity and grazing capacity of pastures. It is also poisonous to livestock and humans and has caused deaths in cattle, sheep and poultry. It is seldom consumed fresh by livestock, but may be dangerous if it contaminates fodder or chaff. Severe gastroenteritis is the main symptom of poisoning by this species. Contact with the sap can also cause skin rashes and other symptoms in humans (Lloyd & Peirce 2003).

Narrow Leaf Cotton Bush is also regarded as an environmental weed in Western Australia, New South Wales, Tasmania, Victoria and Queensland (WWF 2006). It is a common weed of grasslands, open woodlands and disturbed sites and also invades riparian areas. It competes with native plants in these habitats and is capable of forming dense thickets. Narrow Leaf Cotton Bush is currently of utmost concern as an environmental weed in New South Wales and Western Australia, where it often invades conservation areas. For example, Narrow Leaf Cotton Bush was recently listed as a moderately important species in the Environmental Weed Strategy of Western Australia and was also listed among the top 20 priority environmental weed species in the Namoi Catchment, in the inland parts of northern New South Wales. It is also listed as a common environmental weed of the Adelaide region in South Australia (Navie & Adkins 2007).

How does it spread?

Narrow Leaf Cotton Bush reproduces by seed. Suckers may also be produced off lateral roots that are close to the soil surface. The fluffy seeds are most commonly spread by wind and float on water. They may also be dispersed as a contaminant of agricultural produce (e.g. fodder) or in mud attached to animals, machinery and other vehicles (Parsons & Cuthbertson 2001).

What is its history in Australia?

Narrow Leaf Cotton Bush was most probably introduced as a garden plant during the early days of settlement in Australia. It probably came to this country as a result of trade with the Cape Colony in southern Africa and was already present in Sydney by 1802 (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Narrow Leaf Cotton Bush has a shallow root system so small infestations can be dealt with by hand pulling or grubbing. However, care should be taken to remove the crown and as many roots as possible to minimise suckering. Material should also be disposed of carefully to prevent spreading the seeds. Appropriate measures should also be taken to avoid contact with the toxic sap, such as wearing rubber gloves and overalls, and washing hands thoroughly before eating (Lloyd & Peirce 2003, Parsons & Cuthbertson 2001).

Larger infestations are best dealt with by a combination of spraying herbicides, slashing and pasture management (Lloyd & Peirce 2003). Slashing or mowing populations during the winter can be effective over time, as long as seedlings and regrowth is slashed again or treated with herbicides before flowering occurs (Parsons & Cuthbertson 2001).

Glyphosate and triclopyr are recommended herbicides for the control of Narrow Leaf Cotton Bush in Western Australia (Lloyd & Peirce 2003). However, check with your local council or state/territory government agency about its requirements for control of Narrow Leaf Cotton Bush.

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)

Seeds of Narrow Leaf Cotton Bush can germinate at any time during the warmer months of the year, providing adequate soil moisture is available. However, there are usually peaks in germination during late spring and early autumn. Growth is rapid during the warmer months, but it slows or ceases during winter (Parsons & Cuthbertson 2001). Flowering occurs from spring through until early autumn (August to April), but is most abundant during summer. The fruit are present from late summer through to late spring (February to December) (Navie & Adkins 2007).

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?

Narrow Leaf Cotton Bush is widely naturalised in Australia with a scattered distribution throughout the southern and eastern parts of the country. It is most common and widespread in the coastal and sub-coastal regions of eastern New South Wales and in south-western Western Australia. However, it is also present in many parts of South Australia, in western and central Victoria, in Tasmania, in the inland parts of southern New South Wales and in south-eastern Queensland (Navie & Adkins 2007).

Where does it originate?

Narrow Leaf Cotton Bush is native to southern and eastern Africa (from South Africa to Ethiopia, Somalia and Eritrea) and the Arabian Peninsula (Oman, Yemen and the southern parts of Saudi Arabia). There are several subspecies, and the one that is thought to be widely naturalised in Australia and in other parts of the world has a more limited distribution in southern Africa (in southern Angola, Namibia, South Africa, Swaziland, Lesotho, Malawi, Zambia, Zimbabwe, Mozambique and Botswana) (Goyder & Nicholas 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

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

Gomphocarpus fruticosus

Other scientific names (synonyms)?

• Asclepias fruticosa L.
• Gomphocarpus fruticosus (L.) R. Br.

Does it have other known common name(s)?

Narrow-Leaved Cotton Bush, Narrowleaf Cottonbush, Swan Plant, Swanplant, Milk Weed, Milkweed, Cape Cotton, Duck Bush, Swan Bush, Wild Cotton