Silky oak | |
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In flower in Israel | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Proteales |
Family: | Proteaceae |
Genus: | Grevillea |
Species: | G. robusta |
Binomial name | |
Grevillea robusta | |
Grevillea robusta, commonly known as the southern silky oak, silk oak or silky oak, silver oak or Australian silver oak, [1] is a species of flowering plant in the family Proteaceae. Despite its common names, it is unrelated to true oaks, which belong to the family Fagaceae. Grevillea robusta is a tree, and is the largest species in its genus. It is a native of eastern coastal Australia, growing in riverine, subtropical and dry rainforest environments.
Grevillea robusta is a fast-growing evergreen tree with a single main trunk, growing to 5–40 m (20–100 ft) tall. The bark is dark grey and furrowed. Its leaves are fern-like, 10–34 cm (4–10 in) long, 9–15 cm (4–6 in) 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. [2] [3] [4]
The flowers are arranged in one-sided, toothbrush-like groups, sometimes branched, 12–15 cm (5–6 in) long. The carpel (the female part) of each flower has a stalk 21–28 mm (0.8–1 in) 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. [2] [3]
Grevillea robusta was first formally described in 1830 by Robert Brown after an unpublished description by Allan Cunningham.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 . [5] [6] The specific epithet (robusta) is a Latin word meaning "strong like oak" or "robust". [7]
Silky oak occurs naturally on the coast and ranges in southern Queensland and in New South Wales as far south as Coffs Harbour 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, Lord Howe Island 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. [1] [2] [8]
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. [4]
Recently,[ when? ]G. robusta has been used for side and back woods on guitars made by Larrivée and others, because of its tonal and aesthetic qualities.[ citation needed ]
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 −8 °C (18 °F). [9] 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. [10]
G. robusta is often used as stock for grafting difficult-to-grow grevilleas. It has been planted widely throughout the city of Kunming in south-western China, forming shady avenues.
G. robusta is grown in plantations in South Africa, [11] and can also be grown alongside maize in agroforestry systems. [12]
In the UK, G. robusta has gained the Royal Horticultural Society's Award of Garden Merit. [13] [14]
The flowers and fruit contain toxic hydrogen cyanide. [15] Tridecylresorcinol in G.robusta is responsible for contact dermatitis. [16]
Grevillea longifolia, commonly known as fern-leaf spider flower, is a species of flowering plant in the family Proteaceae and is endemic to the Sydney Basin in New South Wales. It is an erect to spreading shrub with narrowly egg-shaped to almost linear leaves, and toothbrush-like groups of pinkish-fawn flowers with a pink to red style. It is fairly readily grown in gardens.
Orites excelsus, commonly known as prickly ash, mountain silky oak or white beefwood, is a species of flowering plant in the family Proteaceae and is endemic to eastern Australia. It is a medium-sized to tall rainforest tree with oblong to lance-shaped leaves, variously lobed and with teeth on the edges. The flowers are white and arranged in leaf axils in spikes that are shorter than the leaves.
Grevillea lanigera, commonly known as woolly grevillea, is a species of flowering plant in the family Proteaceae and is endemic to south-eastern continental Australia. It is a spreading shrub with narrowly oblong to more or less linear leaves and clusters of pink to red, and cream-coloured flowers.
Grevillea bipinnatifida, commonly known as fuchsia grevillea, is a species of flowering plant in the family Proteaceae and is endemic to the south-west of Western Australia. It is a spreading shrub, usually with bipinnatifid leaves and loose clusters of dull pink to crimson flowers.
Grevillea crithmifolia is a species of flowering plant in the family Proteaceae and is endemic to the south-west of Western Australia. It is a dense shrub with linear leaves, divided leaves with narrowly oblong lobes, or both, and clusters of pale pink to creamy-white flowers.
Grevillea caleyi, also known as Caley's grevillea, is a critically endangered species of flowering plant in the family Proteaceae and is endemic to a restricted area around the Terrey Hills and Belrose area in New South Wales. It is an open, spreading shrub, growing up to 4 m (13 ft) tall with deeply divided leaves with linear lobes, and fawn flowers with a maroon to red style.
Grevillea agrifolia, the blue grevillea, is a species of flowering plant in the family Proteaceae and is native to the north of Western Australia and parts of the Northern Territory. It is a shrub or tree with narrowly oblong leaves with the narrower end towards the base, and creamy-yellow flowers.
Grevillea pectinata, commonly known as comb-leaf grevillea, is a species of flowering plant in the family Proteaceae and is endemic to the south of Western Australia. It is a spreading shrub with divided, comb-like leaves and mauve-pink to red and cream-coloured to yellow flowers with a red to deep pink style.
Hakea lorea, commonly known as bootlace oak or cork tree, is a species of shrub or small tree in the family Proteaceae found in central and northern Australia. It has needle-shaped leaves, yellow, white or green flowers and hard corky bark.
Persoonia rigida, commonly known as the rigid-, hairy- or stiff geebung, is a species of flowering plant in the family Proteaceae and is endemic to south-eastern Australia. It is an erect to low-lying shrub with hairy young branchlets, lance-shaped to spatula-shaped leaves that are hairy when young, and yellow flowers borne in groups of up to twenty on a rachis up to 90 mm (3.5 in) long that continues to grow after flowering.
Hakea tephrosperma commonly known as hooked needlewood, is a shrub or small tree species in the family Proteaceae. It has cream flowers, needle-shaped leaves and is one of the taller species in its genus, adaptable for dry to temperate locations.
Grevillea floribunda, commonly known as seven dwarfs grevillea, is a species of flowering plant in the family Proteaceae and is endemic to eastern Australia. It is a spreading shrub with oblong to egg-shaped leaves with the narrower end towards the base and groups of six to twenty flowers covered with rusty brown hairs.
Grevillea quercifolia, commonly known as the oak-leaf grevillea, is a species of flowering plant in the protea family and is endemic to the southwest of Western Australia. It is a straggly to sprawling shrub usually with pinnatifid or serrated leaves, and oval to cylindrical clusters of pale to deep pink flowers.
Grevillea triternata is species of flowering plant in the family Proteaceae and is endemic to New South Wales. It is a dense, compact shrub with divided leaves, the end lobes sharply pointed, linear to narrowly triangular, and cylindrical clusters of white flowers with a cream-coloured to pale yellow style.
Grevillea divaricata is a possibly extinct species of flowering plant in the family Proteaceae and is endemic to central New South Wales. It is a low shrub with linear leaves and small clusters of flowers on the ends of branchlets. It is only known from the type specimen, discovered in 1823. No live specimens have been found since then.
Grevillea depauperata is a species of flowering plant in the family Proteaceae and is endemic to the south-west of Western Australia. It is a low, dense, spreading shrub with oblong or egg-shaped leaves and clusters of red to orange flowers.
Grevillea fasciculata is a species of flowering plant in the family Proteaceae and is endemic to the south-west of Western Australia. It is a low, often spreading shrub with narrowly elliptic to more or less linear leaves and erect clusters of red and orange or orange and yellow flowers.
Grevillea anethifolia, commonly known as spiny cream spider flower, is a species of flowering plant in the family Proteaceae and is endemic to continental Australia. It is an erect shrub with hairy branchlets, lobed leaves, the lobes sharply pointed, and white to pale yellow or cream-coloured flowers.
Grevillea baxteri, commonly known as the Cape Arid grevillea, is a flowering plant of the family Proteaceae and is endemic to the south-west of Western Australia. It is an erect to spreading shrub with pinnatipartite leaves and greenish to fawn or creamy-orange flowers.
Grevillea angulata is a species of flowering plant in the family Proteaceae and is endemic to the Top End of the Northern Territory. It is a spreading to erect shrub with pinnatifid or toothed leaves and cream-coloured flowers.