Grevillea Robusta
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''Grevillea robusta'', commonly known as the southern silky oak, silk oak or silky oak, silver oak or Australian silver oak, is a species of flowering plant in the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Proteaceae The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genus, genera with about 1,660 known species. Australia and South Africa have the greatest concentr ...
. Despite its common names, it is unrelated to true oaks, which belong to the family
Fagaceae The Fagaceae (; ) are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with around 1,000 or more species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species ...
. ''Grevillea robusta'' is a tree, and is the largest species in its
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
. It is a native of eastern coastal Australia, growing in riverine,
subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
and dry rainforest environments.


Description

''Grevillea robusta'' is a fast-growing evergreen tree with a single main trunk, growing to tall. The bark is dark grey and furrowed. Its leaves are fern-like, long, wide and divided with between 11 and 31 main lobes. Each lobe is sometimes further divided into as many as four, each one linear to narrow triangular in shape. It loses many of its leaves just before flowering. The flowers are arranged in one-sided, toothbrush-like groups, sometimes branched, long. The
carpel Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more ...
(the female part) of each flower has a stalk long. The flowers are glabrous and mostly yellowish orange, or sometimes reddish. Flowering occurs from September to November and the fruit that follows is a glabrous follicle.


Taxonomy and naming

''Grevillea robusta'' was first formally described in 1830 by
Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...
after an unpublished description by Allan Cunningham. The type specimen was collected by Cunningham on the eastern edge of Moreton Bay in 1827. Brown's description was published in '' Supplementum primum Prodromi florae Novae Hollandiae''. The
specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
(''robusta'') is a
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
word meaning "strong like oak" or "robust".


Distribution and habitat

Silky oak occurs naturally on the coast and ranges in southern
Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...
and in
New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
as far south as
Coffs Harbour Coffs Harbour, locally nicknamed Coffs, is a coastal city on the Mid North Coast of New South Wales, Australia, north of Sydney, and south of Brisbane. It is one of the largest urban centres on the North Coast, with a population of 78,759 a ...
where it grows in subtropical rainforest, dry rainforest and wet forests. It is now relatively rare in its natural habitat but has been widely planted. It has become naturalised in many places, including on
Norfolk Island Norfolk Island ( , ; ) is an States and territories of Australia, external territory of Australia located in the Pacific Ocean between New Zealand and New Caledonia, directly east of Australia's Evans Head, New South Wales, Evans Head and a ...
,
Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Port ...
and the Atherton Tableland in Australia, and overseas in South Africa, New Zealand, Hawaii, French Polynesia, Jamaica and Florida. It is regarded as a weed in parts of New South Wales and Victoria, and as invasive in Hawaii and South Africa.


Uses

Before the advent of aluminium, ''Grevillea robusta'' timber was widely used for external window joinery, as it is resistant to wood rot. It has been used in the manufacture of furniture, cabinetry, and fences. Owing to declining ''G. robusta'' populations, felling has been restricted. The flowers of ''Grevillea robusta'' produce a rich nectar, which Indigenous Australians traditionally consumed either directly from the blossom or by shaking the nectar into water.


Cultivation

When young, it can be grown as a houseplant where it can tolerate light shade, but it prefers full sun because it grows best in warm zones. If planted outside, young trees need protection on frosty nights. Once established, it is hardier and tolerates temperatures down to . It needs occasional water but is otherwise fairly drought-resistant. Care needs to be taken when planting it near bushland because it can be invasive. ''G. robusta'' is often used as stock for
grafting Grafting or graftage is a horticulture, horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the roots ...
difficult-to-grow grevilleas. It has been planted widely throughout the city of
Kunming Kunming is the capital and largest city of the province of Yunnan in China. The political, economic, communications and cultural centre of the province, Kunming is also the seat of the provincial government. During World War II, Kunming was a Ch ...
in south-western China, forming shady avenues. ''G. robusta'' is grown in plantations in South Africa, and can also be grown alongside
maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
in agroforestry systems. In the UK, ''G. robusta'' has gained the
Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...
's
Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...
.


Toxicity and allergic reactions

The flowers and fruit contain toxic
hydrogen cyanide Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...
. Tridecylresorcinol in ''G.robusta'' is responsible for
contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes ...
.Menz, J., Rossi, R., Taylor, W.C, Wall, L., Contact dermatitis from Grevillea " Robyn Gordon", ''Contact Dermatitis'', Vol. 15, Iss. 3, pp 126-131, Apr 2006 Image:Silveroak.jpg, silky oaks planted in a tea plantation Image:Grevillea robusta trunk bark 01.jpg, trunk bark Image:Grevillea robusta leaf 01.jpg, leaf Image:Grevillea robusta_flowering_05.jpg, flowering branches Image:Grevillea robusta_flowers_01.jpg, flowers Image:Grevillea robusta_unripe_seed_pods_01.jpg, unripe seed pods Image:Grevillea robusta leaves and dry seed pods.jpg, leaves and dry seed pods Image:Grevillea robusta dry seed pod.jpg, dry seed pod Image:Grevillea robusta_seeds_01.JPG, seed pod and seeds Image:Grevillea_Robusta.jpg, Flowering branches Image:Grevillearobusta40181608300 6dbb4fe9b0 o.jpg, seed pods Image:Flowers, robusta.jpg, branch end with
inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...
Image:A tree of Koubilla (Grevillea robusta) species growing inside the Kangla fort in Imphal, Kangleipak (Manipur).jpg, Tree in Kangla Fort


References


External links


Plants of Hawaii (images): ''Grevillea robusta''
{{Authority control robusta Trees of Australia Proteales of Australia Flora of New South Wales Flora of Queensland Garden plants of Australia Ornamental trees Drought-tolerant trees Plants described in 1830