White Oak (Grevillea Baileyana)
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JANUARY 2014 TM YOUR ALERT TO NEW AND EMERGING THREATS. 1. 2. 3. 4. 1. Habit in cultivation. 2. Immature fruit. 3. Entire leaves on adult plant. 4. Close-up of densely packed cream flowers. White Oak (Grevillea baileyana) Quick Facts Introduced Native Not Declared > A tree growing up to 30 m tall, but TREE usually less than 10 m in height White Oak is an attractive tree of the Proteaceae plant family that > Variable leaves that range from is native to the rainforests of northern Queensland and Papua New deeply lobed to entire Guinea. It is widely grown as a garden and street tree and is particularly > Leaves have distinctive rusty brown common in cultivation in the sub-tropical regions of Australia. undersides > Cream flowers densely arranged in elongated clusters Distribution White Oak is native to north-eastern Queensland and the southern coastal regions of Papua New > Small fruit that split open to release Guinea. In Queensland it is restricted to two main areas, from the McIlwraith Range to the vicinity of a single papery seed Coen and from Cooktown south to Ingham. While no herbarium records have been collected outside its native range, there are reports of young plants becoming established in bushland in the Brisbane and Sunshine Coast areas. For example, Habitat several seedlings and saplings have been reported from conservation reserves in Kuraby, Larapinta Within its native range, White Oak typically grows and Tingalpa in Brisbane. Numerous young plants have also been recorded becoming established in in rainforests and their margins, from sea level the vicinity of mature adult trees in the Tewantin and Noosaville areas on the Sunshine Coast. up to 900 m altitude. It is also found in riparian vegetation and gallery forests, and is most common Description in regrowth areas. A tree growing up to 30 m tall, but usually less than 10 m in height in cultivation. Its trunk and older branches have grey bark while its younger stems and new growth is covered in rusty brown hairs. The alternately arranged leaves are variously shaped depending on the age of the plant. Leaves of younger plants and regrowth are usually quite large (up to 30 cm long) with 5-9 prominent lobes (each 3-11 cm long and 15-30 mm wide). Leaves of seedlings and adult plants are usually smaller (10-20 cm long and 1-6 cm wide), and are either entire or have a few small lobes towards their tips. The upper leaf surfaces are dark green while the lower surfaces are distinctly rusty brown. The white flowers are borne in elongated clusters at the tips of the branches in late spring and early summer. These clusters (6-14 cm long) are cream in colour and usually held upright. Each cluster contains numerous small, densely packed, flowers which have inconspicuous petals and a very conspicuous style ending in a swollen stigma. The small fruit (12-19 mm long and 7-9 mm Documented herbarium record wide) turns from green to brown as it matures and splits open when fully mature to release a single Native range papery seed (11-12 mm long and 6-7 mm wide). Potential introduced range © Technigro Australia Pty Ltd 2014 JANUARY 2014 TM YOUR ALERT TO NEW AND EMERGING THREATS. 1. 2. 3. 4. 5. 1. Young sapling growing in a swamp box forest. 2. Rusty brown leaf undersides. 3. Deeply-lobed leaves on regrowth. 4. Showy flower clusters in November. 5. Seedling growing in a scribbly gum forest. Reproduction and Dispersal This species reproduces only by seeds, which are primarily wind-dispersed. However, Look a-likes White Oak can be confused with White Silky seeds may also be spread in dumped garden waste. Oak (Grevillea hilliana), Ivory Curl (Buckinghamia celsissima) and other closely related members of Why is it an Emerging Threat? the Proteaceae. However, White Oak can be easily White Oak is favoured by disturbance and is a characteristic species of regrowth areas distinguished from these species by its rusty brown within its native range. Hence, it is probably well adapted to colonising areas of disturbed leaf undersides. The flower clusters of Ivory Curl are forest outside its native range. also drooping in nature, instead of being held upright. Evidence from this very early stage of invasion suggests that it favours wetter habitats in south-eastern Queensland (i.e. disturbed rainforests, wet sclerophyll forests and tea tree swamps). In some cases plants have become established hundreds of metres away from cultivated specimens, in undisturbed natural vegetation. Control Methods As most plants invading natural areas are currently quite small they can usually be pulled out by hand. Larger plants can be manually removed with the aid of suitable tools, but care must be taken to remove the entire crown. No herbicides are specifically registered for the control of White Oak in Australia, but Vigilant Gel is registered for the control of woody weeds in native vegetation, conservation areas, gullies, reserves and parks (using the cut-stump method). Woody environmental weeds may also be controlled with some herbicides in Queensland as outlined in APVMA off-label Permit 11463 (see http://permits.apvma.gov.au/PER11463.PDF). For example, some formulations of glyphosate and triclopyr + picloram can be applied as a cut stump or basal bark application. Please read the off-label permit carefully for the exact products and rates to use and, unless otherwise stated in the permit, the use of any of these herbicides must be in accordance with the instructions on their labels. Within other state boundaries, Top. Ivory Curl leaves with pale green undersides. it is recommended that any relevant permits or government legislation applicable to the Bottom. Drooping flower clusters of Ivory Curl. region be consulted. The control methods referred to in Weed Watch™ 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 utilisation 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, Technigro does not invite reliance upon it, nor accept responsibility for any loss or damage caused by actions based on it. This information has been developed with the assistance of Dr Sheldon Navie. Photographs are also courtesy of Dr Sheldon Navie © Technigro Australia Pty Ltd 2014 Your Provider of Vegetation Management Solutions Post: PO Box 2020, Nerang BC, QLD, 4210 T: 1800 678 611 technigro.com.au for smarter solutions.