Click on images to enlarge
infestation (Photo: Forest and Kim Starr, USGS)
habit (Photo: Sheldon Navie)
close-up of furrowed bark on main trunk (Photo: Sheldon Navie)
younger leaves (Photo: Sheldon Navie)
compound leaf with deeply-divided leaflets (Photo: Sheldon Navie)
paler leaf underside (Photo: Sheldon Navie)
flower clusters (Photo: Sheldon Navie)
close-up of flowers (Photo: Sheldon Navie)
clusters of immature fruit (Photo: Forest and Kim Starr, USGS)
mature fruit that have already released their seeds (Photo: Sheldon Navie)
close-up of seeds (Photo: Steve Hurst at USDA PLANTS Database)
young seedling (Photo: Sheldon Navie)
Grevillea robusta A. Cunn. ex R. Br.
Australian silky oak, silk oak, silk-oak, silkoak, silky oak, silver oak, southern silky oak
Native to some parts of eastern Australia (i.e. south-eastern Queensland and north-eastern New South Wales).
Naturalised beyond its native range on the northern tablelands of New South Wales and sparingly naturalised in northern Victoria. It is also known to be naturalised in the coastal districts of central New South Wales, though this is not backed up by herbarium specimens. Also naturalised on Lord Howe Island and Norfolk Island.
Naturalised overseas in South Africa, New Zealand, Hawaii, French Polynesia, Jamaica and south-eastern USA (i.e. Florida).
Silky oak (Grevillea robusta) is regarded as an environmental weed in New South Wales and as a minor environmental weed or potential environmental weed in Victoria. This species grows naturally in sub-tropical rainforests and in wet sclerophyll forests on the coast and inland ranges north of the Coffs Harbour district in New South Wales. It is widely cultivated as a garden ornamental and street tree in Australia and has escaped cultivation and become invasive outside its natural range.
Silky oak (Grevillea robusta) is currently of particular concern throughout the wider Sydney and Blue Mountains region in central New South Wales. For example, it is mentioned as a common environmental weed at Hunts Creek in western Sydney and has become naturalised in Lane Cove National Park in northern Sydney. It is also a known weed in the lower Blue Mountains and is one of three native plants that are problem weed species in the Shoalhaven Shire, to the south of Sydney.
In Victoria, silky oak (Grevillea robusta) is also beginning to demonstrate weedy tendencies. It appears on the environmental weed list for the Goulburn Broken Catchment and is listed as a minor environmental weed in the City of Boroondara in Melbourne. Overseas, silky oak (Grevillea robusta) is listed among Hawaii's most invasive horticultural plants, is reported to be invasive in Florida, and is classed as a "Category 3 invader" in South Africa.
Fact sheets are available from Department of Employment, Economic Development and Innovation (DEEDI) service centres and our Customer Service Centre (telephone 13 25 23). Check our website at www.biosecurity.qld.gov.au to ensure you have the latest version of this fact sheet. The control methods referred to in this fact sheet should be used in accordance with the restrictions (federal and state legislation, and local government laws) directly or indirectly related to each control method. These restrictions may prevent the use of one or more of the methods referred to, depending on individual circumstances. While every care is taken to ensure the accuracy of this information, DEEDI does not invite reliance upon it, nor accept responsibility for any loss or damage caused by actions based on it.
Copyright © 2016. All rights reserved. Identic Pty Ltd. Special edition of Environmental Weeds of Australia for Biosecurity Queensland.
The mobile application of Environmental Weeds of Australia is available from the Google Play Store and Apple iTunes.