Boneseed, like many of our environmental weeds, was first introduced to New Zealand for use as an ornamental plant. Native to South Africa, a lack of pests and disease in New Zealand has allowed it to grow unchecked.
Botanical Name
Chrysanthemoides monilifera
Background
Boneseed is now recognised as a plant pest throughout New Zealand and is included in Canterbury’s Regional Pest Management Strategy for Biodiversity Pests. The objective for boneseed, or salt bush as it is sometimes known, is removal of all existing plants from areas outside the Port Hills and a 20% reduction of infested areas within the Port Hills area over the next 10 years.
Why is it a problem?
A tolerance of dry, infertile soils allows boneseed to colonise and establish easily in coastal areas. Its vigorous growth will displace desirable plants, shade out native seedlings and reduce or prevent public access to coastal and beach areas. It is highly flammable and will regenerate prolifically after fire.
Description
Boneseed is an evergreen shrub reaching up to 3 metres. The leaves are dull green, toothed and covered with a cottony down. Daisy-like flowers are produced in bright yellow clusters from late winter until late summer. Boneseed gets its name from its hard, bone-coloured seed. This seed has a thin, fleshy cover - initially green but changing to black upon ripening. Up to 50,000 seeds per plant can be produced in a year and can remain viable for up to 10 years. Seed dispersal is by birds and water.
Control
Control of boneseed is relatively easy. Hand pull small plants. Larger plants should be cut just above ground level and the stump immediately treated with an appropriate herbicide. Removed plants should be taken to refuse stations, or composted if all seeds are removed. Follow up care will be needed as any seed remaining on the ground will germinate rapidly once the soil is disturbed and the area is opened to light.