Quick Facts

Quick facts

• Originally from South Africa, Boneseed (Chrysanthemoides monilifera subsp. monilifera), a Weed of National Significance, is a small evergreen shrub with yellow flowers, and an aggressive invader of intact native bush-land in southern Australia.
• Without effective control, Boneseed has the potential to significantly increase and become more abundant within its current range in native undisturbed vegetation ranging from dunes, mallee, native grasslands and scrub, woodlands and open forests, in particular in coastal fringe and open vegetation.
• Boneseed produces large quantities of seeds (up to 50,00 produced per plant) which are spread long distances by native and feral animals and birds, water, and down slopes by gravity, forming persistent seed-banks.
• Numerous control option are available both physical and chemical, but any control efforts must be long-term to prevent re-establishment of populations from seed-banks and re-introduction from existing populations.
• Prevention is the most cost-effective form of weed control. Quarantine, early detection and good hygiene within infestations will prevent its spread.

What Does It Look Like?

What is it?

Boneseed (Chrysanthemoides monilifera subsp. monilifera) is a erect evergreen shrub, perennial being relatively short-lived (10-20 years), which grows up to 2-3 m high, reproducing (spreading) only by seed. It has woody branched stems. Leaves are  20–70 mm long, and 10–35 mm wide, shaped elliptic (broadest in the middle and equally narrow at both ends) to broadly elliptic to obovate (egg-shaped to triangular in outline with the widest part nearer the tip of the leaf), with irregularly serrated edges. Leaves are fresh green, thick and soft-leathery, with a obvious mid-vein. New growth is typically covered by white downy cotton-like material (hairs). Boneseed has a shallow root system. It can absorb moisture from light summer showers before it reaches the deeper rooting zone of other plants. This gives it a competitive advantage over deeper-rooted species, especially in areas of low summer rainfall (CRC 2003).

The inflorescence (flowers heads), are in groups of 3-12. Individual flower heads are up to 30 mm in diameter with each flower head with 5-8 fresh bright yellow petals around the edge and a deeper yellow centre, with peak flowering occurring from August to October. Each flower head is made up of many individual flowers crowded on to a receptacle at the end of the flower stalk. Flower heads are made up of two kinds of flowers, disc flowers (also known as tubular florets (or tubular flowers) in the centre that are the darker looking, and 5-8 ray (ligulate), flowers around the edge are the flower head that appear to be individual petals, but are in fact individual 'ray' flowers. 

The fruit is round drupe (like a fleshy berry) to 8-9 mm in diameter across, fleshy green, turning black when mature, and contains a single smooth round seed 6-7 mm in diameter. The seed is bone coloured when dry, hence the name 'Boneseed' (CRC 2003).

Recognition: This species can normally be recognised by the combination of the following characters; Woody stems are branched and upright; Leaves are 20-70 mm long and alternate along the stems, egg-shaped with irregularly serrated edges are thick and soft-leathery. New growth is covered with white hairs; Flower heads are in groups of 3-12, yellow with 5-8 petals and up to 3 cm in diameter. Peak flowering occurs from August to October. Young fruit is round, green and fleshy and turn black when mature. They contain a single, smooth, round seed (6-7 mm diameter) which is bone-coloured when dry, giving rise to the name ‘boneseed’.

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

Flower colour

Yellow

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

Boneseed grows under a wide range of climatic conditions but prefers sandy or medium-textured soils and disturbed situations, particularly near the sea because it tolerates salty conditions (CRC 2003). It prefers winter rainfall regions. Boneseed does not tolerate waterlogged conditions, and growth is inhibited by prolonged droughts and frosts (Brougham et al. 2006).

Are there similar species?

Boneseed can be confused with the closely related Bitou Bush (Chrysanthemoides monilifera subsp. rotundifolia). Boneseed differs from Bitou Bush by its upright growth habit (versus the sprawling habit of Bitou Bush), less rounded and more obviously toothed leaves, flowers with less petals. (5-8 for Boneseed versus 11-13 for Bitou Bush) and round, smooth seeds (versus usually smaller and darker egg-shaped ribbed seeds for Bitou Bush). Bitou Bush is also mainly confined to coastal areas with summer rainfall (Adair & Ainsworth 2000; Brougham et al. 2006).

Similar natives found in coastal habitats are:

Boobialla (Myoporum insulare) and Sea Box (Alyxia buxifolia). Both grow mostly on sea cliffs and have round or fleshy leaves. Boobialla is the most similar, with fleshy bright green leaves, white shortly tubular flowers spotted purple inside and succulent purple fruits. Sea Box has round leathery leaves, white flowers and red berries. Juvenile Boneseed in particular can be confused with seedlings of the Boobialla. However, Boneseed seedlings are covered in white downy hair while Boobialla seedlings are not (Brougham et al. 2006).

Hop Goodenia (Goodenia ovata), a weak shrub with thin, brown, erect stems, shiny, finely toothed leaves and bright yellow flowers mainly in spring to summer could also be confused with Boneseed. However, the flowers are 5-petalled, irregular and not daisy-like (DPI 2001).

Why Is It A Weed?

What are its impacts?

Boneseed is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. Without effective control programs, Boneseed has the potential to become more abundant within its current range and to spread into new areas. Most of southern Australia, including Tasmania, is threatened by Boneseed. For example, a recent climate analysis has shown that virtually all of Victoria is potentially suitable for infestation by Boneseed (CRC 2003).

Agriculture: Boneseed is not an agricultural weed and does not persist when grazed and trampled by stock, nor when land is cultivated (CRC 2003).

Native ecosystems: Boneseed has become an aggressive invader of native bush-land in Australia. Each plant produces large quantities of seed (up to 50,000 per mature healthy plants) that is readily dispersed long distances by native and feral animals allowing Boneseed infestations to establish in areas of undisturbed vegetation ranging from dunes, mallee, native grasslands and scrub, woodlands and sclerophyll forests including to Eucalyptus dominated forests, and in particular, the coastal fringe and open or scrub. Once established, its rapid regeneration and ability to spread quickly after disturbance such as fire or clearing allows it to out-compete and displace native species (CRC 2003; Brougham et al. 2006).

Boneseed It is also a threat to a number of significant rare or threatened species (DPI NSW 2019). It is listed as a threat to some populations of Pterostylis truncata (Brittle Greenhood), a species listed under the Victorian Flora and Fauna Guarantee Act 1988. The Coast Manna-gum (Eucalyptus viminalis subsp. pryoriana) vegetation association on the Mornington Peninsula, Victoria has been severely degraded as a result of Boneseed invasion (CRC 2000), Eucalyptus microcarpa and E. porosa woodlands in SA, E. ovata. E. viminalis, and E. globulus in TAS, and eastern suburbs Banksia scrub communities in Sydney.

Urban areas:  Not normally a weed of urban areas but can spread along roadsides and occupy vacant areas of land where no grazing exists.  Only rarely seen as a garden plant.

How does it spread?

Seed is the method of reproduction in Boneseed as it does not reproduce vegetatively (such as by suckers and cuttings) (Brougham et al. 2006).

Birds, including Emus, attracted to the fleshy fruits, are a major method of spread along with Rabbits, Foxes and Cattle. The smooth round seeds also disperse from the parent plant by rolling down slopes, and the hard seed coat allows seeds to remain viable when transported via either fresh or salt water. Boneseed has also been spread by the dumping of garden waste and by transportation of its seeds on machinery. Gravel carted from the You Yangs in Victoria has been a major method of spread from the infestation there (CRC 2003; Brougham et al. 2006).

What is its history in Australia?

The exact date and manner of introduction of Boneseed into Australia is unknown although it was probably originally planted as a garden species and to stabilise sand dunes. It was first recorded as a garden plant in Macleay's Garden in Sydney in 1856. Many current infestations can be attributed to garden escapes. It was first recorded in the wild in 1852 in Sydney and 1892 in Adelaide, where it escaped from horticulture (CRC 2003). Self-sustaining populations established quickly, and it is thought that Boneseed was naturalised in Australia by 1910 (Parsons & Cuthbertson 1992).

How To Manage It?

Best practice management

Considerable research and effort has been made into the control of Boneseed. As a result a range of effective control measures are available, including chemical, physical and biological control methods, also incorporating the use of fire. Because of the large and persistent seed-banks in the soil, long-term control will mean that areas have to be treated repeatedly for several years (CRC 2003). Prevention of infestation in the first instance is clearly a priority. Any Boneseed plants in gardens should be destroyed since they represent a seed source and hence potential for further spread (CRC 2003).

Chemical control: Chemicals (herbicides) can be used to control bone seed with 4 main methods used.

1. Cut-and-swab method where herbicide is applied to the stump of a felled plant.

2. Stem injection method where herbicide is injected in the sapwood of the plant in the main stem.

3. Foliar spray method where the leaves of the plant are sprayed with a herbicide solution.

4. Splatter gun application method where

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

Physical control: Because of its shallow root system with no large taproot, seedlings and young plants can be pulled out by hand. Larger plant may be able to be hand pulled in damp moist soil or in sandy soil. This is not possible in heavier drier soils and the use of hand tools is required to leaver plants out of the ground (e.g. the tree popper). 

Biological control: Boneseed has also been recognised as a target for biological control through a cross-jurisdictional government process. Attempts at biological control of Boneseed not been hugely successful so far (Brougham et al. 2006). Boneseed has been targeted for biological control but the control agents already released, including the tip moth Comostolopsis and the seed fly Mesoclanis, have failed to establish successfully. The leaf buckle mite Aceria and the rust Endophyllum osteospermi appear more promising agents. Natural regeneration or over-sowing with locally collected seed of native species can be an important part of the rehabilitation process (CRC 2003).

See the link below for detailed information on planning for and undertaking control of Boneseed as seen in 'Boneseed Management Manual' (available at https://www.environment.nsw.gov.au/research-and-publications/publications-search/boneseed-management-manual-current-management-and-control-options-for-boneseed).

Does it have a biological control agent?

YES. One of the agents released for boneseed is the leaf-buckle mite, (Aceria sp.) (Hervey et al., 2023).

When does it grow? (lifecycle/growth calendar)

Boneseed grows rapidly during winter and a few plants may flower in the first year, particularly on burnt areas where there is little competition. However, plants are usually at least 18 months and sometimes three years old before flowering. Flowers are formed in late winter and spring but not shed until summer, unlike Bitou Bush which flowers almost year round with a peak from April to June. Seeds germinate at any time of the year but mostly in autumn. An individual plant can produce 50 000 seeds a year and about 60% of seeds are viable. The hard seed coat splits open in some and these germinate as soon as there is enough soil moisture. In many seeds however, the seed coat remains intact and seeds can remain viable in the soil for more than ten years (CRC 2003).

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?

Boneseed occurs over a wide area of southern Australia, especially in Victoria along the Mornington Peninsula where remnant Manna Gum (Eucalyptus viminalis) vegetation is under threat, and in the You Yangs. Infestations also occur in the Mount Lofty Ranges, South Australia; parts of the Tasmanian north and east coasts; the south and central coasts of New South Wales; and near Perth in Western Australia (CRC 2003).

Boneseed has the potential to significantly increase its range, and also become more abundant within its current range. Climate-based analysis predicts that the potential distribution of Boneseed extends across southern Australia, with the exception of the Nullarbor Plain and areas subject to extreme frosts (Brougham et al. 2006).

Where does it originate?

Both the subspecies of Chrysanthemoides monilifera present in Australia are native to South Africa. Boneseed is restricted to south-western South Africa where it is found on hilly terrain.

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

YES

Where is it a declared weed?

Declared in all states and territories.

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

Chrysanthemoides monilifera subsp. monilifera

Other scientific names (synonyms)?

Does it have other known common name(s)?

Boneseed