Hakea leucoptera is a plant of the dry regions of Australia. The species is often referred to as silver needlewood, needle hakea, pin bush, and water tree. It has several indigenous names; Booldoobah, Uri, Kuluva, and Kuloa. The specific epithet, derived from the Latin Leucoptera (Gk): leuco means "white"; and ptera means "winged", referring to the characteristic white-winged seeds of this species.
Taxonomy and naming
The two subspecies differ only in the nature of the hairs on the rachis of the inflorescence, those of ssp. leucoptera being white woolly pubescent (raised), while those of ssp. sericipes are shining white or brown and appressed (not raised).
Hakea leucoptera was treated as part of the Sericea group, a predominantly eastern states group characterised by their simple terete leaves, few-flowered inflorescences, hairy pedicels and solitary, prominently woody fruits, these often markedly verrucose or pusticulate and usually with horns. Other members of the group are H. actites, H. constablei, H. decurrens, H. gibbosa, H. kippistiana, H. lissosperma, H. macraeana, H. macrorrhyncha, H. ochroptera, H. sericea and H. tephrosperma, predominantly from the eastern states of Australia.
Hakea leucoptera and H. tephrosperma are often confused. Initially they can often be distinguished by the mucro, curved in H. tephrosperma and usually porrect in H. leucoptera. H. tephrosperma also has a shorter floral rachis with rust-coloured hairs, and the pedicel and perianth are densely appressed-pubescent, while H. leucoptera has a longer floral rachis. Pubescent flowers in H. leucoptera seem to be confined to S.A. and N.T.
Hakeas are closely related to the genus Grevillea and Finschia, both members of the subfamily Grevilleoideae within the family Proteaceae. Many species have similar inflorescences, but hakeas can be distinguished by their woody seed pods. Hakeas belong to the family Proteaceae, which includes such well known plants as Banksias, Grevilleas and Waratahs.
There are around 150 species of Hakeas and they are only found in Australia. They occur in most areas of Australia in a wide range of habitats. Many are found in arid areas but they also occur in forests and heath lands and swampy areas.
Many Hakeas have narrow leaves with sharp points which lead to common names such as "needle bush" and "needle points" This is an adaption to avoid drying out as very little leaf area is exposed to the sun and moisture loss from the leaf surface is reduced.
Most Hakeas are shrubs, some are low ground-hugging plants and others are small trees to about 10 metres. The flowers of most Hakeas resemble those of their close relative, Grevilleas with auxiliary clusters or racemes.
One of the main distinguishing features between Hakeas and Grevilleas is that Hakeas have woody fruits. The fruits open into two valves to reveal two seeds with a membranous wing. The seeds fit into cavities in the woody case and many make very attractive designs when the seed is released. Many of the seed cases are decorative. Some are quite large. Many have unusual shapes or they are rough with "bubbly" warts or tubercules which add interest and texture to a garden. Some Hakeas have long racemes up to 20 centimetres long. Hakea bucculenta and Hakea francisiana do not respond well to growing in the open garden on their own rootstock in eastern NSW. Some success has been achieved from grafting. Hakea salicifolia is most frequently used as rootstock.
Hakea victoria has been called ‘the world's most beautiful foliage plant’ whereas others think it is grotesque. The leaves are round, stiff, curved upwards and up to 12 centimetres in diameter. They have prickly, toothed, wavy edges and a conspicuous network of veins. Their most unusual feature is the colour. Each leaf has a green rim with the centre of the leaf changing in colours over the years from yellow to orange to red. One of the best known is Hakea laurina, known as the pin-cushion hakea because of its round flower heads, which can adapt more readily to eastern NSW.
Habit and leaf form
The habit of this plant is highly variable. It can be a small open branched tree to 5 m or a small multi stemmed shrub to 3 m. The habitat is usually course textured soils and associated with a wide variety of species in woodland communities. It is widespread throughout all mainland states occurring in dense thickets of shrubs, as scattered individual trees or a large parent tree surrounded by offspring. It has a reddish-brown close-grained timber that is soft but hard and brittle when dry. Hakea leucoptera resembles an oak tree. They can shoot from roots or by suckering. Many species develop lignotubers or a swollen rootstock as they grow older. This is a source of regrowth in times of drought or fire. Some attention is required when plants are young to get them established in respect of water requirements. Once actively growing they require very little attention.
The leaves are arranged alternatively along the branches. They are rigid and cylindrical in varying length from 8–35 mm long and approximately 1.5 mm wide with a sharp pointed tip. The young leaves are hoary but as they mature they become smooth.
Inflorescence and floral features
Creamy white flowers are formed on short hairless stalks about 4 mm long in clusters of 20 or more as auxiliary racemes. Hakea leucoptera flower from late spring to summer.
Fruit and seed features
Fruit comprises a woody follicle about 20–30 mm long which is swollen at the base but tapers to a point. The capsules open in halves longitudinally revealing 2 seeds that have an opaque wing on one side only. The woody seed can persist on the branches until after the following years flowering. Immature seed will not ripen off the plant and it is best to collect older fruits. Crop size varies from year to year. Once removed the fruits usually dry out and open within 1–2 weeks. It is easily grown from fresh seed which usually germinates in 3–6 weeks and seed is suitable for direct seeding.
Shrubby forms are palatable to stock but only in times of acute feed shortage.
This plant was important to the Indigenous people and inland explorers as they sourced water from the roots. The tree was burnt which forced the water into the root system, then the roots were dug up. They were stripped, one end placed over a slow fire while the other over a container to force the water out. This feature also enabled the plant to quickly regenerate after fire.
A sweet nutritious drink was made by dipping heavily laden blossom into a cup of water or by sucking the flowers directly. Hakea leucoptera flowers produce a high quality honey favoured by bees.
The Indigenous people of inland Australia used corkwoods as a medicinal agent. Burns and open sores were directly applied with the burnt bark of the Hakea tree or the burnt bark mixture was combined with animal fat to make a healing ointment.
The seed pods were also used for decoration by Indigenous people. The timber polishes up well and haves a very showy grain and was also used for small tannery articles.
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