Acacia auriculiformis A. Cunn.
Darwin Black Wattle
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
Used for fuelwood plantations as an ornamental and shade tree, quite tolerant
of heat, the Australian species is widely planted in Oceana and southeast Asia.
The wood is also employed for making farm tools and furniture (NAS, 1983a).
Recent Australian tests suggest that 10-year old trees can be pulped readily by
the sulfate process, giving high pulp yields, with good strength properties.
Also produces high quality pulp by the neutral sulfite semichemical process.
The tannin produces a good quality leather, inclined to redden upon exposure to
sunlight (NAS, 1980a). The plant is amazing in its ability to recolonize
wastes, papermill sludge, pH ca 9.5; even uranium spoils, pH ca 3.0; the only
tree found on 20-year old uranium spoil. Used for the cultivation of the lac
insect in India.
No data available.
The gum contains 5.3% ash, 0.92% N, and 1.68% methoxyl, and ca 27.7% uronic
acid. The sugar from the gum after hydrolysis, contained 10.1%
4-0-methylglucuronic acid, 17.6% glucuronic acid, 59% galactose, 8% arabinose,
and 5% rhamnose (Anderson, 1978). Bark contains ca 13% water.
Resilient, vigorously growing, crooked or gnarled deciduous or evergreen tree,
possibly attaining 30 m height, 60 cm DBH. Leaves alternate, simple flattened
phyllodes, lanceolate or oblong, arcuate, long-attenuate at both ends, 1016 cm
long, ca 1.52.5 cm broad, thick coriaceous, glabrous with several long
parallel veins from the base. Spikes 58 cm long, paired at the leaf bases.
Flowers sessile, ca 3 mm long, the calyx glabrous, 5-toothed, the 5 petals ca 2
mm long. Stamens numerous, filiform, ca 3 mm long. Ovary pubescent, the style
filiform. Pods 68 cm long, 11.5 cm broad, flattened but coiled. Seeds
several, flattened-ellipsoid, ca 5 mm long, with a reddish or orangish aril
(Little, 1983). Seeds 53,00062,000/kg.
Reported from the Australian Center of Diversity, Acacia auriculiformis,
or cvs thereof, is reported to tolerate alkalinity, desiccation, drought, fire,
high pH, laterite, poor soil, sand dunes, and savanna. It is intolerant of
hurricane, shade, and weeds, at least in early stages. Once established, the
tree is quite competitive with weeds. Though somewhat tolerant of fire, it is
not so resistant as Eucalyptus. (2n = 26)
Native to the savannas of New Guinea, islands of the Torres Strait, and
northern Australia, it has been widely introduced, e.g. in Fiji, India,
Indonesia, Java, Malaysia, Niger, Nigeria, Philippines, Tanzania, Thailand, the
Soloman Islands, Uganda, and Zanzibar.
Estimated to range from Subtropical Moist to Wet through Tropical Dry to Wet
Forest Life Zones, Acacia auriculiformis is reported to tolerate annual
precipitation of 7.5 to 27 dm, annual temperature of 26 to 30°C, and pH of
3.0 to 9.5. With practically no maintenance it will grow on a wide range of
deep and shallow soils, compacted clays, coral soils, laterites, limestone,
mica schist, mine spoil, podzols, even sand dunes and unstable slopes.
It has been suggested as an interplant with long-term timber Dalbergias, itself
serving as a short-term but renewable firewood source. Seeds, storable for 18
months in airtight containers, should be soaked in hot water for 24 hours. Sow
in full light, allowing 6 days for germination (ca 80% germination after 24
weeks). To reforest grassland, burn and plant in holes ca 36 x 30 x 30 cm,
spaced at 12.5 or 13 m if intercropped with Cassia siamea. Recent
spacings have been 2.5 x 2.5 m.
In Indomalaysia, stands are operated on 1012 year rotations. Trees coppice
poorly. Indonesians have gotten some coppice when trees are cut at least 50 cm
above the ground. When trees are felled, there is usually a swarm of
seedlings, so cutover stands regenerate readily.
With rainfall at 2700 mm, at 3 years, average height of a stand with 1010
trees/ha was 12.4 m, average diameter 12.2 cm, standing wood volume 73.2 m3/ha;
at age 4, 13.1 m, 13.6 cm, and 96.1 m3/ha. Stemwood volume is ca 60% of total
above ground biomass. Leaf biomass is important, the LAI being 78, good for
shading out weeds. Average amount of dead litter is 4800 kg/ha. In Java,
there may be 3 MT/ha leaves and 2 MT/ha twigs and branches beneath the trees
(NAS, 1982a). On infertile abandoned sites in Papua, trees grew 6 m in 2
years, 17 m in 8 years. On shallow arid soils in West Bengal, yields were only
5m3/ha/yr at the 15th year. Under moister conditions 10 m3 is reported, 1720
in Indonesia and Malaysia.
Wiersum and Ramlan report that yields can run higher than 20 m3/ha/yr on a
1020 year rotation. On poor soils yields drop to 812 m3. On the Island of
Madura, with annual rainfall 17001900 mm, 712 year old rotations run 7.69
m3/ha/yr, but on West Bengalese laterites with annual precipitation
1,00014,000 mm, yields are only 26 m3/ha/yr in 1020 year rotations. With
its capacity to produce good fuelwood on poor soils, even where there are
extended dry seasons, the species "merits large scale testing as a fuelwood
species" (NAS, 1980). Wood has specific gravity of 0.60.75 and calorific
value of 4,8004,900 kcal/kg. Wood yields excellent charcoal that glows well
and burns without smoke or sparks. Litter beneath the trees, both branches and
dried leaves, annually adds up to 4.56 MT/ha, all used for fuel in China.
Hawaiian grown material possesses N-fixing nodules.
While no pest or disease problems are reported in Indonesia, insects and
nematodes have been reported to attack seedlings in Zanzibar. The rust
Uromyces digitatus has been a problem in Java, where it is also
occasionally infested with a rather inocuous black mildew, Meliola
adenanphererae. In India, the root rots are Ganoderma lucidum and
Ganoderma applanatum. Hypothenemus dimorphus has caused shoot
fatality in Malaysia. The weevil Hypomeces squamosus can be a pest in
India and Malaysia. Used to cultivate Kerria lacca in India. On Java,
the ant Iridomyrmex rufoniger may protect the plant from some
Complete list of references for Duke, Handbook of Energy Crops
- Anderson, D.M.W. 1978. Chemotaxonomic aspects of the chemistry of acacia gum
exudates. Kew Bull. 32(3):529536.
- Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their
identification. McClain Printing Co., Parsons, WV.
- N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production.
National Academy of Sciences, Washington, DC.
- N.A.S. 1982. Priorities in biotechnology research for international
development. Proceedings of a Workshop. National Academy Press, Washington,
- N.A.S. 1983a. Producer gas: another fuel for motor transport. National Academy
Press, Washington, DC.
Last update Tuesday, January 6, 1998 by aw