Silky Oak is a flowering, timber and agroforestry tree originating from Australia, its natural range limited to pockets of subtropical forest on the east coast of the continent.
It is a fast-growing tree, to heights of up to 35 m (114 ft) in its natural habitat, though elsewhere it is more typically 15 to 25 m (50 to 80 ft) tall and develops a straight trunk supporting a pyramidal or rounded crown. The bark is grey-brown and fissured.
Leaves fern-like, dark green on top, silvery beneath and in a dense arrangement that casts a deep shade. They remain on the tree where the dry season is short but fall where it is long or pronounced, leaving the branches mostly bare for a short period, just before flowering.
Flowers thin, erect, orange-yellow tubes, in long clusters that somewhat resemble a brush with bristles. They bloom in perfusion from spring to early summer, with the most striking displays seen on near leafless trees.
Fruit small, flat, oval seedpods which, when mature, are dark brown to near black with one or two small winged seed inside.
Silky Oak is widely cultivated in urban parks and landscapes, especially in its native Australia, for its spectacular flowering, eye-catching foliage and the shade it gives.
Long ago introduced into India, Sri Lanka and Kenya, it is cultivated there as a shade tree, to shade crops such as tea and coffee, on account of its fast growth and good adaptation to tropical highland climates. It is also cultivated for the production of fuelwood, for both firewood and charcoal, as well as for protective windbreaks and honey production.
The flowers produce good quantities of nectar and it is reported as a honey tree in Australia and in countries where it is introduced, including India, Tanzania, Guatemala and the Dominican Republic. The honey is dark amber with a pronounced flavour, dense texture and is quick to granulate to a smooth grain. The nectar also helps to nourish and sustain nectar eating birds in its native range, making it an important wildlife tree.
The wood is medium-weight, in the 540 to 660 kgs per cubic meter (34 to 41 lbs per cubic ft) range, has attractively figured pinkish-brown heartwood and is moderately resistant to rot and decay, making it fit for indoor and some outdoor applications.
Well-formed logs are sawn into planks used mostly for fine furniture, cabinets, interior flooring, interior house trim, doors, window-frames and the like. Selected logs are sliced for decorative veneer and the branch-wood, apart from fuelwood, is used in turnery.
Silky Oak develops a good form in sub-humid to humid subtropical and tropical mid- to high-elevation climates, generally areas with annual lows of 9 to 19 °C, annual highs of 19 to 32 °C, annual rainfall of 700 to 2400 mm and a dry season of 7 months or less.
Trees may fail to flower, or flower poorly, in extreme high-elevation areas, such as in Bogotá (Colombia), Addis Ababa (Ethiopia) and Mexico City, generally areas where the average low of the warmest month is below 14 °C (57 °F). In Hawaii, the best-developed trees are to be found in mid-elevation areas with annual rainfall of 1500 to 2000 mm.
New plants are usually raised from seed, which remain viable for up to a year under cold, dry airtight storage and germinate within thirty days of sowing.
Silky Oak trees perform best on free-draining clay-loam, loam and sandy-loam soils of an acid to neutral nature, generally with a pH of 4.5 to 7.5 and on sites with full to partial sun exposure.
The winged seeds are carried by the wind over long distances and germinate readily. It has naturalised in many areas where it is introduced and in some areas has become an undesirable weed. In South Africa, it is recorded as a serious invader of the natural ecosystem and it is assessed to be a high weed risk for Hawaii, by the Hawaii Pacific Weed Risk Assessment project (HPWRA).
The branches are brittle and are prone to breakage in strong winds, potentially causing personal injury or damage to property. The flowers, fruit and sap may cause dermatitis in some and the fallen leaves create litter.
Adams, C. D. 1972, Flowering plants of Jamaica, University of the West Indies, Mona, Greater Kingston
Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London
Boland, D. & Brooker, I. & McDonald, M. W. 2006, Forest trees of Australia, 5th ed., CSIRO Publishing (Ensis), Melbourne
Bradbear, N. 2009, Bees and their role in forest livelihoods : a guide to the services provided by bees and the sustainable harvesting, processing and marketing of their products, Food and Agriculture Organization of the United Nations (FAO), Rome
Burke, D. 2005, The complete Burke's backyard : the ultimate book of fact sheets, Murdoch Books, New South Wales, Australia
Burns R.M., Mosquera M.S. & Whitmone J.L. 1998, Useful trees of the tropical region of North America, North American Forestry Commission Publication (Number 3), Washington D.C.
Burns, R.M. & Honkala, B.H. 1990, Silvics of North America (Volume 2) : Hardwoods, Agricultural Handbook 654, U.S. Department of Agriculture (USDA), Washington D.C.
Chudnoff, M. 1984, Tropical timbers of the world, Forest Service, U.S. Department of Agriculture (USDA), Washington, D.C.
Clarke, B. & McLeod, I. & Vercoe, T. 2009, Trees for farm Forestry : 22 Promising Species, Rural Industries Research and Development Corporation (RIRDC), Wagga Wagga, New South Wales
Crane, E., Walker, P. & Day, R. 1984, Directory of important world honey sources, International Bee Research Association, London
Doran, J. C & Turnbull, J. W. 1997, Australian trees and shrubs : species for land rehabilitation and farm planting in the tropics, 2nd ed, Australian Centre for International Agricultural Research (ACIAR), Canberra, Australian Capital Territory
Gilman, E. F. 1997, Trees for urban and suburban landscapes, Delmar Publishers, Albany, New York
Hall, N. 1972, The use of trees and shrubs in the dry country of Australia, Australian Government Publishing Service, Canberra, Australian Capital Territory
Holliday, I. 2002, A field guide to Australian trees, 3rd revised editon, New Holland Publishers, Frenchs Forest, New South Wales
Jensen, M. 1999, Trees commonly cultivated in Southeast Asia : an illustrated field guide, 2nd ed., Food and Agricultural Organisation of the United Nations (FAO) Regional Office for Asia and the Pacific (RAP), Bangkok
Jex-Blake, A. J. 1957, Gardening in East Africa : a practical handbook, 4th ed., Royal Kenya Horticultural Society, Longmans, Green and Company, London
Jones, R. 2001, Caring for cut flowers, 2nd ed, Landlinks Press, Victoria, Australia
Krishen, P. 2006, Trees of Delhi : a field guide, Dorling Kindersley Publishers, Delhi
Little, E. L. & Skolmen, R. G. 1989, Common forest trees of Hawaii (native and introduced), Agricultuural Handbook No. 679, Forest Service, U.S. Department of Agriculture, Washington, D.C.
Luna, R. K 1996, Plantation trees, International Book Distributors, Dehradun, Uttarakhand
Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London
Nair, P. K. R. 1993, An introduction to agroforestry, International Centre for Research in Agroforestry (ICRAF), Kluwer Academic Publishers, Dordrecht
National Research Council (Board on Science and Technology for International Development) 1980, Firewood crops : shrub and tree species for energy production (Volume 1), The National Academies Press, Washington D. C.
Scheffer, T. C & Morrell, J. J. 1998, Natural durability of wood : a worldwide checklist of species, Forest Research Laboratory, Oregon State University, Corvallis, Oregon
Sheikh M. I. 1993, Trees of Pakistan, USAID Forestry Planning and Development Project, Pictorial Printers, Islamabad
Smith, F. G. 2003, Beekeeping in the tropics, Northern Bee Books, Hebden Bridge, West Yorkshire
Vozzo, J. A 2002, Tropical tree seed manual, U.S. Department of Agriculture (USDA), Forest Service, Washington D.C.
Webb, D. B. 1984, A Guide to species selection for tropical and sub-tropical plantations, 2nd ed., Unit of Tropical Silviculture, Commonwealth Forestry Institute, University of Oxford, Oxfordshire
Johnson, A. & Johnson, S. 2006, Garden plants poisonous to people, New South Wales Department of Primary Industries (NSW DPI), Orange, New South Wales
Morton, J.F. 1964, Honeybee Plants of South Florida, Proceedings of the Florida State Horticultural Society, Vol 77:415-436.
Skolmen R.G. 2000, Some woods of Hawaii: properties and uses of 16 commercial species, University of Hawaii, Honolulu, (Resource Managment; RM-7), 33 p.
This website is provided for general information only. Iplantz makes no statements, representations or warranties as to the accuracy or completeness of the content of this website and does not accept any liability to you or any other person for the information which is provided or referred to on this website.
In particular, Iplantz does not represent or warrant that any dataset or the data it contains is accurate, authentic or complete, or suitable for your needs. Changes in circumstances after the time of publication may impact the accuracy of datasets and their contents.
To the maximum extent permitted by law, Iplantz accepts no liability whatsoever to any person arising from or connected with the use of or reliance on any information or advice provided on this website or incorporated into it by reference, including any dataset or data it contains. No responsibility is taken for any information or services that may appear on any linked websites.