Suppression

Acacia melanoxylon (Australian blackwood)

Category: Medicines - plant based

Type

Voluntary

Introduction and description

 

Acacia melanoxylon, commonly known as the Australian blackwood, is an Acacia species native to eastern Australia. The species is also known as Sally wattle, lightwood, hickory, mudgerabah, Tasmanian blackwood, black wattle or blackwood acacia.

Uses

Wood - Acacia melanoxylon has generated interest outside the Australian aboriginal community for its highly decorative timber which may be used as a cabinet timber, for musical instruments or in boatbuilding. In effect the interest is entirely commercial.  This logging based money making venture has received something of a blow however, as a result of the following [one of many papers which say the same thing]

Australian blackwood is known to be an important cause of allergic contact dermatitis in Australia. Previous investigations have shown that 2,6-dimethoxy-1,4-benzoquinone and acamelin are 2 of the responsible, but weak, sensitizers. When these 2 quinones are lacking, which is occasionally found, the wood still possesses allergenic properties. The present re-examination led to the isolation and identification of 4 hydroxyflavans, of which 3 proved to be allergens. Melacacidin, known to be the main constituent of these flavan derivatives in the heartwood, was isolated and its sensitizing capacity in guinea pigs determined. It showed a moderate sensitizing power. Melacacidin occurs abundantly in 125 Australian and 3 African Acacia species. PMID: 2144805

Flowers - According to Plants for a Future the flowers can be eaten, they used as their source A. B. and J. W. Cribb’s Wild Food in Australia. We have our doubts about this as flowers are only edible if there is some advantage to the plant in reducing the number and there appears to be no advantage in this case.  Given that the flowers are also described as having a ‘penetrating scent’, the prospect of eating them does not sound too attractive.

Medicinal - Within the indigenous peoples however, it is known medicinally.  Australian Aborigines treated Rheumatic joints, for example, with a heated infusion of roasted bark.  The presence of tannin in the bark gives it several other important medicinal properties. The bark has a tannin content of about 20%.

Description

Acacia melanoxylon is an evergreen tree growing to 30 m (98ft 5in) at a fast rate.  It lives for around 15 – 50 years. It is hardy and even tolerates frost.  This is one of the hardier members of the genus, tolerating temperatures down to about -10°c.

 

It produces both phyllodes (basically a flattened stem that looks and acts like a leaf) and true leaves.

The roots are very vigorous and extensive - they often produce suckers and can damage the foundations of buildings if planted.

Acacia melanoxylon  produces attractive flowers or blooms. The flowers are hermaphrodite (have both male and female organs). They are pom pom like and a soft yellow in colour.

 It is a successional species, regularly producing large numbers of well-dispersed seeds. Seed viability is sufficiently long to bridge the time between successive seedling stages.

It can fix Nitrogen.  It has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.

Habitats

It tolerates drought, poor drainage,  salt air, gusty, steady or cold winds if grown in the open, fog, smog, and temperature extremes. It is happy in agricultural areas, coastland, disturbed areas, estuaries, natural forest, planted forests, range/grasslands, riparian zones, scrub/shrublands, and urban areas.

It prefers a sandy loam and a very sunny position and thrives in a hot dry position. The only thing it does not like is soil that is too limey. Most members of this genus become chlorotic on limey soils.

In South-east Queensland it is an important host plant for a number of indigenous butterfly larvae, including tailed emperor (Polyura sempronius); silky hairstreak (Pseudalmenus chlorinda); imperial hairstreak (Jalmenus evagoras evagoras); stencilled hairstreak (Jalmenus ictinus) and large grass-yellow (Eurema hecabe hecabe).

Acacia melanoxylon has been introduced to many countries as an ornamental tree. It is now present in Africa, Asia, Europe, Indian Ocean, the Pacific Ocean, South America and the United States. It is a declared noxious weed species in South Africa and is a pest in Portugal's Azores Islands. It was also recently listed by the California Invasive Plant Council (Cal-IPC) as an invasive weed. Its use as a street tree is being phased out in some locales because of the damage it often causes to pavements and underground plumbing.

Medicinal uses

See observations

 

Related observations