Boneseed

Chrysanthemoides monilifera.
Family: Asteraceae

Growth Habit: Boneseed is a woody, evergreen shrub that can reach 3m in height. The dull green leaves are leathery to feel with young leaves being covered with a cottony down. The plant is most visible when covered in flower from late winter to summer.

Type of plant: Erect, evergreen perennial shrub.

Flowers: Bright yellow daisy flowers occur at the end of branches from July to October.

Fruit/Seed: Green berries gradually blacken as they ripen. Each plant can produce up to 50,000 seeds annually. Typically the soils beneath these bushes will contain up to 2500 seeds per square metre. Each berry contains one very hard coated seed which can remain viable in the soil for at least five years.

Dispersal: Boneseed is spread by ants, birds and animals feeding on the fruits. Fruits and seeds are also carried by running water. Plant material that has been pulled from one area and dumped in vacant land and along roadsides seems to be significant in spreading the seeds of this weed. Because it is easy to grow and flowers for such long periods, people are still removing seedlings from infested areas and planting it in their gardens.

Distribution: Boneseed is common in the Tamar Valley, along the Northern Coast, at spot locations on the East Coast and in the urban environments in Hobart and Launceston. Recent studies have concluded that this plant is capable of dramatically increasing its range.

Status: Boneseed is a declared weed in Tasmania, although it is a declared Noxious Weed in Victoria, New South Wales, Queensland, South Australia and Western Australia.

Weed Impact:

  • Boneseed is a significant threat to bushland and conservation areas. Vigorous, competitive growth and the ability to regenerate prolifically after fire allows boneseed to dominate and smoother native plants. Once a few bushes have established themselves in an area, any new soil disturbance or fire will trigger off the mass germination of soil stored seed and lead to the dramatic suppression of the native vegetation.
  • Dense stands of boneseed have significantly effected the available food sources and habitat for native birds and animals while favouring introduced ones such as blackbirds and sparrows.
  • Though boneseed is an evergreen, it is flammable and dense stands can represent a significant fire risk. Boneseed is able to colonise inhabitable or disturbed sites. In the past it was used for reclaiming these types of sites. Boneseed is not a significant agricultural weed because it is readily grazed by stock and it will not withstand cultivation or trampling.

For further information on boneseed contact the Department of Primary Industry, Water and Environment, Tasmania (Service Sheet, 56/93. Agdex 642).

Control Methods:

  • Chemical (all year). Both foliar spraying and cut stump application can be used on boneseed. For details on herbicides and rates see boneseed Weeds Leaflet or Herbicide Recommendations for Weed Control in Tasmania – Non Crop Situations.
  • Replant (all year). After controlling existing boneseed plants, revegetate the area to suppress seedling growth.
  • Bio-control (all year). A biological control agent, the black boneseed beetle (Chrysolina progressa) is available for release in Tasmania. More details are available from the Department of Primary Industry and Fisheries.
  • Grazing (Oct – Jan). The use of controlled grazing in early summer when plants are tender especially after an initial burn, will control young seedling growth.
  • Grubbing (all year). Grubbing and hand pulling should be done prior to flowering but require a follow up due to seedling flushes.
  • Burning (Sept – Jan). Burning on a 1-2 year frequency will control most of an infestation. Some follow up will be necessary. This treatment is not suited to all situations.

N.B. Always check the herbicide label before use.