Family: Fabaceae
Common name: Acacia, Earleaf acacia, Black wattle, Wattle, Bengali babul, Northern black wattle, Earleaf acacoa, Earpod wattle, Tan wattle, Darwin black wattle, Auri, Karuvel
Earleaf acacia is a fast-growing tree very commonly seen in India and other tropical countries, grown as ornamental trees, and also for its wood.
The tree is native to Australia, Indonesia, and other Southeast Asian countries, growing well in warm, moist weather.
Tree characteristics
Earleaf acacia trees grow to a height of 20-30 meters with an open, spreading crown of about 8-10 meters. The bark is about 50 cm in diameter, crooked, gnarly, and fissured with a brown or grayish-brown color.
The tree is covered with dark green foliage providing shade and shelter, and also arousing interest due to the unique shape of the leaves. Earleaf acacia leaves are long, narrow, and curved like a sword. These are modified leaf stems called phyllodes and not true leaves.
They are 15-20 cm long and 3-6 cm wide with parallel veins that are quite prominent. There is no mid-rib, only multiple parallel ribs running along the length of the leaves.
The margins of these leaves are smooth, sometimes slightly wavy. The unique earlobe shape of the leaves give the tree its name Earleaf acacia.
Flowers of the Earleaf acacia tree are very prominent though they are small, since they bloom in large clusters. Each flower is about 1-3 cm in diameter with five petals and a small tuft of stamens that give them a fluffy appearance.
Flowering happens from Dec to March attracting a variety of pollinators to the tree.
Earleaf acacia fruits are 6-8 cm long, initially green, later turning dark brown. They are straight when the fruits are young, but become twisted and gnarly as they seeds inside mature and are about to be released.
The pods split open on maturity to release the seeds. Young fruits and seeds are eaten by birds and small animals that are also help in dispersing the seeds on maturity. Earleaf acacia seeds are small and black, about 4-6 mm long.
Gardening tips
Earleaf acacia trees grow in tropical and subtropical climate in well-drained soil, but they are capable of growing in a variety of soil conditions like sandy, loamy, and clayey.
These trees grow very well near beaches and are tolerant of salinity in soil and wind. They also grow very well in home gardens giving shade, and beautifying the garden with their leaves and flowers.
The bright, beautiful flowers that bloom in abundance can attract pollinators like bees and insects to the garden. And the edible fruits attract small birds, and animals like squirrels.
Earleaf acacia trees do not need watering and tending once they are established in the soil. And hence they make good trees for landscaped areas that can be ignored for months and years. They also tolerant of drought and most pests.
Pruning can be done to keep the tree well-rounded and attractive, though they usually grow in a neat, compact shape by themselves.
Uses of Earleaf acacia trees
These trees have various medicinal and commercial uses. They are mostly grown as ornamental trees or for firewood. Parts of the tree are used in treating rheumatism, wounds, cuts, skin irritations, digestive issues, diarrhea, and eye infections.
Since these trees belong to the beans and peas family of Fabaceae, their roots contain nitrogen-fixing bacteria that can improve the soil quality by converting atmospheric nitrogen into nitrates and nitrites that can be absorbed by plants.
The bark contains tannins that are used commercially for tanning animal skins. Earleaf acacia trunk produces a gum that is sold commercially.
Young leaves can be eaten raw or cooked, though this is not very common. Wood from the tree is used for making small furniture, toys, and tool handles.
Fiber from the tree is used for making paper pulp, and there are large-scale plantations of Earleaf acacia trees grown only for this purpose.
In addition, these trees provide shade, shelter, and food for humans and other animals, promoting a thriving ecosystem around it. They also prevent soil erosion when planted near beaches or sloped land, holding fast the topsoil to prevent it from running away.
Propagation
Propagation is through seeds and stem cuttings.
Each tree produces abundant seeds that can be collected when they are mature, soaked in warm water, and then planted in moist soil to germinate. Stem cuttings taken from semi-hard trunks can also root well in soil, though the success rate might not be very high.
Photographed at: Chethy beach, Alleppey, Kerala
