Boneseed

NOXIOUS WEED: Class 4

Chrysanthemoides monilifera ssp monilifera

family: ASTERACEAE (daisy family)

Description

  • Boneseed is a garden ornamental, introduced into Australia from South Africa more than a century ago. Boneseed has been declared a Weed of National Significance, ie, one of the worst weeds in Australia, because of its invasiveness, potential for spread, and economic and environmental impacts.
  • Boneseed is a vigorous evergreen much-branched erect woody shrub to 2m or more in height and width; it grows in a wide range of climatic conditions and soils, tolerates periods of drought but not waterlogging, and thrives on disturbed sites.
  • Roots are shallow, stems are hairless, green when young, becoming woody with age.
  • Leaves are 3-8cm long, oval-shaped with irregularly toothed edges; young leaves are light green and covered with a white cotton-like material, mature leaves are dull green, leathery and hairless.
  • Flowers are bright yellow and daisy-like, to 30mm in diameter, have 5 to 8 petals, and cluster at the ends of the branches. Boneseed flowers profusely, mostly from August to October.
  • Fruit is green and fleshy at first, maturing to black, the outer covering flaking off to reveal the single hard round seed, 5-7mm in diameter, bone-like in colour and texture. Boneseed produces up to 50,000 seeds per plant, and the soil may contain up to 2,500 seeds per square metre.
  • Bitou Bush (Chrysanthemoides monilifera ssp. rotundata), a look-alike and close relative of Boneseed, was for many years planted along the NSW coast to stabilise sand dunes. It now dominates coastal vegetation. Bitou Bush has a more sprawling habit, flowers have 11-13 petals, leaves are not toothed, and flowering is year round but mostly in autumn. It too is a Weed of National Significance - if found, it should be removed.

Boneseed

On some parts of the NSW coast the entire
landscape is dominated by Bitou Bush.
photo: © Hillary Cherry

Dispersal

Seeds are dispersed by birds and animals which eat the fruit, ants which carry it to their nests, the dumping of garden waste, the movement of contaminated soil, and by planting in gardens. Beware of seedlings at garden clubs and fetes.

Impact on Bushland

Boneseed is an aggressive and destructive plant which has the capacity to invade undisturbed bushland, forming dense stands which replace native vegetation, prevent access, restrict germination, and reduce biodiversity. Massive numbers germinate rapidly after fire, outcompeting native plants, and completely dominating the habitat.

Distribution

To date, Boneseed has only been found on a few sites in the Mountains (Woodford, Lawson, Wentworth Falls, Medlow Bath), so we are in the fortunate position where quick action can prevent major damage. Boneseed has the potential to spread throughout most of southern NSW, including the entire Blue Mountains district.

Alternative Planting

native plants:
Sunshine Wattle (Acacia terminalis), Drumsticks (Isopogon anethifolius or anemonifolius), Pine-leaf Geebung (Persoonia pinifolia), Broad-leaf Wedge Pea (Gompholobium latifolium), Hop Goodenia (Goodenia ovata), Tick Bush (Kunzea ambigua).

exotic plants:
Marguerite daisies, Golden Bells (Forsythia viridissima), May Bush (Spiraea spp).

Control

As a Weed of National Significance landowners and occupiers are required to control Boneseed: established plants must be destroyed before they flower and produce fruit.

Both flowers and fruit are found on Boneseed at the same time: whichever method of control you use, be sure to first remove flowers and fruit and send to landfill.

Seedlings can be pulled by hand; small mature plants can be hand pulled too, as the root mass is rather shallow. Rock plant backwards and forwards until it comes out cleanly. It doesn't matter if some roots are left in the ground.

Mature plants can be cut using herbicide - see the cut and paint method. Wrap any seeds and send to landfill. Follow up removing seedlings will be required for some years. Dense monocultures of seedlings can be sprayed.

Biological controls are being trialled, using insects which eat Boneseed and Bitou Bush in their native South Africa, but so far these have not proved very successful with Boneseed.

The current distribution of Boneseed in NSW is shown in yellow, the potential for its spread in green.
photo: © The National Bitou Bush & Boneseed Management group

Noxious Weed Class 4

Class 4: Locally Controlled Weeds

Characteristics: Class 4 noxious weeds are plants that pose a threat to primary production, the environment or human health, are widely distributed in an area to which the order applies and are likely to spread in the area or to another area.

Control Objectives: to minimise the negative impact of those plants on the economy, community or environment of NSW.

Control action: The growth and spread of the plant must be controlled according to the measures specified in a management plan published by the local control authority (BMCC), and the plant may not be sold, propagated or knowingly distributed.

— NSW Noxious Weeds Act of 1993

Boneseed

Boneseed: leaves, flowers and fruit
photo: © Hillary Cherry

Boneseed

Boneseed is a much-branched woody shrub with hairless stems.
photo: © Barbara Harley

Boneseed

Boneseed leaves are toothed; white cottony material is found on young leaves.
photo: © Barbara Harley

Boneseed

Boneseed flowers are bright yellow, with 5-8 petals.
photo: © Hillary Cherry

Boneseed

Boneseed fruits mature from green to black, and contain one hard bone-like seed.
photo: © Barbara Harley

Boneseed

The flowers of Bitou Bush have 11-13 petals, and leaves are not toothed.
photo: © Barbara Harley

Boneseed

Massive numbers of seedlings germinate after fire.
photo: © Barbara Harley

Boneseed

Drumsticks - Isopogon anemonifolius
photo: © Barbara Harley

Boneseed

Seedlings can be pulled by hand; wrap any flowers or seeds and send to landfill.
photo: © Barbara Harley