Boneseed is an evergreen woody shrub growing to two metres or more in height and width. The elongated leathery leaves are dull green in colour and around 40 to 70 mm long and 20 to 35 mm wide.
With its yellow daisy-like flower, you might be tempted to plant in your garden – don’t.
Boneseed flowers from mid-spring to early summer. The yellow flowers develop in clusters at the ends of the branches. The fruits are green and fleshy at first then becoming black at maturity. The fruit eventually flakes off to leave the inner seed exposed.
Boneseed (Chrysanthemoides monilifera ssp. monilifera) originated in South Africa and it was introduced to Australia as a garden plant.
It is a serious environmental weed. Boneseed is a declared weed under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of boneseed are prohibited in Tasmania and non-compliance on importation or removal could results in fines and penalties. Boneseed is also a Weed of National Significance (WONS).
The seeds are hard and bone-like in texture and colour. Seeds are shed during summer and autumn. Heat may crack the seed coat and large numbers of boneseed seedlings may appear after fire.
Boneseed is found across King Island, and it occurs as a weed in disturbed bushland and coastal vegetation. It can invade the understorey of native forests and bushland and is particularly invasive in coastal areas. Boneseed competes with native plants and reduces biodiversity, and dense infestations are a significant fire hazard.
If a property has boneseed the landowner will need a plan and a control program before undertaking removal. Direct any questions to Biosecurity Tasmania, NRE or King Island Landcare.
Slashing or mowing will not eradicate Boneseed as plants regrow strongly from the cut stumps unless they are treated with herbicide.
Never burn boneseed without follow up treatment of regrowth.
Boneseed is spread by birds and animals which eat the fruit, digest the fleshy part and then pass the seed unharmed through the digestive system. Ants can also carry the fruits to their nests where they eat the flesh and discard the seeds. Boneseed fruits and seed are also spread in moving water, livestock movement and by vehicles and machinery.
Seed can be spread in gravel or topsoil collected from areas infested with boneseed. The inappropriate dumping of seeding plants after removal can also lead to spread of the weed.
Vehicles and machinery require wash-down to reduce the chance of spreading boneseed.
Boneseed plants have a relatively shallow root system. Seedlings and young plants can be readily pulled by hand; however larger plants require a tractor or similar equipment.
When bushes are pulled out, the ground disturbance may stimulate seed germination, making the boneseed problem worse. Follow-up treatment including pulling of seedlings or herbicide treatment is essential.
For low to medium boneseed density, hand pull small plants and treat larger plants by cut-stump herbicide treatment. This minimises soil disturbance and damage to native vegetation.
Fire can be used to control dense infestations of boneseed. Burning kills seedlings and most mature plants and stimulates the germination of the seed in the soil. Regrowth seedlings can then be treated by pulling or with herbicide.
A number of herbicides are registered for use on boneseed in Tasmania. See nre.tas.gov.au herbicides suitable for use.
The inappropriate dumping of seeding plants after removal can also lead to spread of the weed.
Most importantly, while the daisy flowers are colourful and it thrives in King Island soils, do not plant boneseed in the garden.