Nepedia
Back to Discover
Advanced Reader
🧬

Acacia decurrens

life science Maturity 5-7 Next article →

Acacia decurrens is a flowering plant species known by many names. You might hear it called black wattle, Sydney green wattle, or early green wattle. It belongs to the Fabaceae family. This plant is endemic to New South Wales and the Australian Capital Territory. This means it is naturally found only in those specific areas.

Acacia decurrensDistMap265
Acacia decurrensDistMap265

However, it has spread far beyond its home. It has naturalized in other Australian states like Queensland and Victoria. It is also found in many other countries, including China, India, and South Africa. In South Africa, it is sometimes called "green cancer" because it has become a weedy species.

Physically, Acacia decurrens grows as a tall shrub or a tree. It can reach heights of up to 10 meters. The bark is often greyish black or black, and it can be smooth or fissured. The leaves are dark green and arranged alternately on a long stem called a petiole. These leaves are bipinnate, which means they are divided into many smaller parts. Specifically, they have 3 to 13 pairs of pinnae. Each of those pinnae contains 15 to 45 pairs of small, linear leaflets called pinnules. The name "decurrens" comes from the Latin word for "running down." This refers to the narrow ridges on the leaves that are continuous with the branchlets.

Acacia-decurrens-catalina
Acacia-decurrens-catalina

The reproductive parts of the tree are quite striking. The flowers grow in spherical heads. These heads are found in elongated clusters called racemes. Each head contains between 20 and 32 bright yellow or golden yellow flowers. The color of these flowers comes from an organic chemical compound called kaempferol. After flowering, the tree produces seed pods. These pods are straight or slightly curved and are thinly leathery. They are often slightly constricted between the seeds. The pods typically mature between November and January.

Acde 001 lhp
Acde 001 lhp

Humans have a long history of studying and naming this plant. In 1798, a German botanist named Johann Christoph Wendland first described it. He originally named it Mimosa decurrens. In 1806, Carl Ludwig Willdenow redescribed it in the genus Acacia as Acacia decurrens. In 2003, a Queensland botanist named Les Pedley reclassified it as Racosperma decurrens. He proposed this because he wanted to move almost all Australian members of the Acacia genus into a new genus. However, most people still treat his name as a synonym for the original name.

The ecology of the wattle is complex and supports many living things. The dark brown or black seeds are the main way the plant reproduces. These seeds can be spread by birds or ants. They can also form a seedbank in the soil. The seedlings often grow very rapidly after a bushfire occurs. This allows the species to colonize disturbed areas quickly. The trees generally live for a period of 15 to 50 years. Many animals rely on the tree for survival. For example, sulphur-crested cockatoos eat the unripe seeds. Various caterpillars, such as the imperial hairstreak, eat the foliage.

Acde 001 lhp
Acde 001 lhp

Acacia decurrens is also very useful to people for many different reasons. The flowers are edible and can be used to make fritters. The tree produces an edible gum from its trunk. This gum can be used as a substitute for gum arabic in making fruit jelly. The bark is also useful because it contains 37% to 40% tannin. People use the flowers to create yellow dye and the seed pods to create green dye. In horticulture, the tree is used as a fast-growing windbreak or a specimen tree in large parks. It is easy to grow by soaking seeds in warm water before sowing them outdoors.

Finally, the plant holds deep cultural and environmental significance. In the Dharawal language, it is known as boo'kerrikin. According to Dharawal stories, one of the Boo'kerrikin Sisters was turned into this plant. For the local people, the flowering of the wattle was a seasonal indicator. It signaled that cold winds were ceasing and gentle rains were beginning. Environmentally, the plant can help create green corridors. Research in the Southern Highlands showed that having these wattles in an area can reduce the numbers of noisy miners. These are aggressive birds that drive other small birds away from gardens and bushland.

701 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (3)
File:Acacia-decurrens-catalina.jpg
Acacia-decurrens-catalina.jpg
File:Acacia decurrensDistMap265.png
Acacia decurrensDistMap265.png
File:Acde 001 lhp.jpg
Acde 001 lhp.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.