tree flowers quickly, within 1-2 years. The tiny yellow flowers are fragrant.
The pods are first straight or slightly curved but as they ripen, they turn
from yellow to brown and curl up, then split open. The black seeds hang
from short curled orange stalks when the pod splits open. Birds find these
seeds highly attractive and eat them. Thus the plant is very quickly dispersed.
Introduced from Australia, the Acacia is a fast growing tree that
grows well even on poor soil. It is now common in wastelands throughout
tree has no leaves except when it is a seedling. When the seedling
first sprouts, it has twice pinnate leaves. Subsequent leaves
have enlarged leaf stalks with a little bit of true leaves and
by the fifth "leaflet", it's all leaf stalk and no
leaf! What you see are flattened leaf stalks called phyllodes,
which are green and function as leaves. These are an adaptation
to hot climates and droughts.
from Wee YC
and wetland wildlife at
Sungei Buloh Nature Park
features: Crooked trunk, reaches 20-30m tall.
Bark: Fissured, grey or brown.
Leaves: None except when
seedling: twice pinnate compound.
Flowers: Clusters, yellow,
small, fragrant. Blooms at certain months of the year.
Fruits: A pod with seeds.
in Singapore: Common in wastelands.
World distribution: Native
to the savannah of New Guinea, islands of the Torres Strait,
and northern Australia, but has since been introduced
to a wide range of countries from Africa to Southeast
Asia and the Pacific islands.
Classification: Family Leguminoseae.
for food: Aborigines of Australia have traditionally harvested
the seeds of some acacia species as food. These are ground into flour and
eaten as a paste or baked into a cake. The seeds can contain 25% more protein
than common cereals like rice or wheat, and their hard seed coats mean acacia
seeds also store well for long periods.
Other uses: Acacias were purposely introduced
and planted in Southeast Asia and Oceania as a source of firewood and good
quality charcoal (does not smoke), as well as timber for furniture and pulp
for making paper (acacia produces high yields of pulp and produces strong
paper). The tannin produced from the tree is of a good quality, but tends
to redden with exposure to sunlight. The tree was also introduced as an
ornamental shade tree, but in Singapore, it is no longer grown as a wayside
tree due to the large amount of litter of "leaves", flowers and
fruits that the tree produces. In India, the tree was cultivated to feed
the lac insect, which produces a resinous secretion that is harvested to
Acacia has the potential to protect poor soils from erosion and revive their
mineral content. Acacia can grow on poor soils including clay, limestone
and unstable sand dunes, even soil tainted with uranium wastes. It is also
able to survive fire, dry spells and seasonally waterlogged soil. (In fact,
the seeds germinate better when placed in hot ashes!). The tree also contains
nitrogen fixing bacteria which can help rejuvenate these poor soils. The
tree prevents soil erosion because of their extensive and dense roots and
heavy leaf litter. But the seedlings don't grow well in the shade and in
competition with weeds, so for deliberate planting, the seedlings have to
raised elsewhere first.
Traditional medicinal uses: A decoction
of the root is used to treat aches and pains and sore eyes; an infusion
of the bark treated rheumatism (aborigines of Australia).
Role in the habitat: Acacias recover
wastelands, returning nutrients to poor soils and providing shade for other
plants to take hold. They do not produce a lot of pollen or nectar as food,
but their plentiful seed supply is a valuable food source for animals (mainly
birds and also small mammals), particularly in dry places. Various insects
eat their leaves and wood, and sugar gliders and squirrels may eat their
sap. The trees also provide shelter for animals; as well as epiphytic plants.
University Centre for New Crops and Plants Products: detailed fact
sheet on its uses, features, chemical composition, habitat.
Forest Project which aims to initiate reforestation by distributing
a wide range of fast growing, nitrogen-fixing tree seeds, that are primarily
for use in the tropics: detailed fact sheet on its habit, habitat, potential
uses to prevent soil erosion and provide useful products.
of Florida, Centre for Aquatic and Invasive Plants: Acrobat .pdf
fact sheet, photo.
Secrets of Aboriginal Bush Medicine: traditional medicinal uses
of the tree.
Tree Resources News Number 1 September 1994 "Humble Wattle
Becomes Life-Saving Food" by Roger Arnold, Project Scientist, Australian
Tree Seed Centre: about the potential of acacias as a food source.
Plant Species in Vietnam's Economy - The Contributions of Australian
Trees from Seminar on Environment and Development in Vietnam Friday
and Saturday, December 6-7, 1996: Use of acacias in Vietnam as a source
of firewood, paper pulp, nitrogen fixers, and other uses.
Island Ecosystems at Risk (PIER) Invasive plant species: fact sheet.
international lots of details on Acacia as a potentially good candidate
for reforestation efforts.
in Queensland on the Queensland Government website: lots of details
on the plant and the wildlife that eat it.
- Wee Yeow Chin,
"A Guide to the Wayside Trees of Singapore", Singapore
Science Centre, 1989 (p. 137-139: description, habitat, photo).
- E. J. H. Corner,
"Wayside Trees of Malaya: Vol I", Malayan Nature Society,
4th ed., 1997 (p. 447-449: description, habit, distribution).
- Science Club,
River Valley High School, "A Guide to the Flora and Fauna of
Schools in Singapore", Hillview Publications, 1991 (p. 6: description,
habits, habitat, photo).
- Anne Nathan and
Wong Yit Chee, "A Guide to Fruits and Seeds", Singapore
Science Centre, 1987 (p. 70: description, habitat, photo).