A great number of shrubs and trees comprise the genus Acacia, which is part of the pea family Fabaceae and the subfamily Mimosoideae. Acacia remains a widely used common name across genera. They grow natively in Africa and Australia, Mediterranean climates, and the grasslands of North America, South America, Europe, and Asia. In the United States, different species of Acacia can be found in California, Texas, Arizona, and Hawaii. Acacia trees and shrubs are technically legumes, meaning they reproduce using seed pods, which are transported by birds, insects, and small mammals. They cannot self-fertilize.
Acacia leaves are compound and bipinnate. They grow in rows that surround a central stem. This gives some species of acacia a feathery, fern-like quality. Not all acacia "leaves" are actually leaves. Some are phyllodes, a type of modified leaf petiole that connects to branches in place of leaf stalks. Some ostensible stems are actually cladodes—essentially photosynthetic stems. Most produce either yellow flowers or white flowers. These flowers have minimal petals and vibrant, showy stamens. They can be found clustered together in either spherical heads or in elongated spikes. The fruits are legumes and are highly variable in appearance, depending on the species.
Table of Contents
13 - 80 feet
Upto 60 feet
4.5 - 9.0
Types of Acacia
Willow Acacia (Acacia salicina)
The Willow Acacia is a sizeable thornless shrub or small weeping tree with slender linear leaves, brown seed pods, and yellow puffball flowers. Depending on Willow Acacia, the plant grows between 10 and 65 ft. (3 – 20 m). The pendulous branches of the willow acacia tree give it a weeping, drooping appearance.
Shoestring Acacia (Acacia stenophylla)
The Shoestring Acacia has long string-like smooth bluish-green leaves and pale-yellow spherical flowers. The Shoestring Acacia grows between 13 and 66 ft. (4 – 20 m) tall and up to 30 ft. (9 m) wide. An identifying feature of Shoestring Acacia is the long seed pods that look like a necklace or rosary beads.
Black acacia (Acacia melanoxylon)
Black acacia is an evergreen acacia known for its dark brown bark, purple fruit, bluish-green leaves, and spiky, creamy white flowers. Some gardeners call it a blackwood acacia.
Bailey Acacia (Acacia baileyana)
The Bailey Acacia is a fast-growing shrubby acacia tree with delicate feathery blue-gray leaves, small golden yellow puffy flowers, and brown seed pods. Also called the Cootamundra Wattle, this acacia tree grows up to 30 ft. (10 m) tall. Its identifying feature is the huge, spreading rounded crown with dense silvery gray-green foliage.
Golden wattle (Acacia pycnantha)
The golden wattle is the national flower of Australia. It is prized for its fragrant yellow blooms and its tannin-rich bark. It grows throughout the southeastern part of the Australian continent.
Silver wattle (Acacia dealbata)
The Silver Wattle is a large evergreen shrub or small tree with silvery-gray twice-compound leaves, golden-yellow globular flowers, and reddish-brown seed pods. This beautiful ornamental yellow acacia is also called ‘Mimosa’ or ‘Blue Wattle.’ This shrub-like tree has rapid growth and grows between 5 ft. and 32 ft. (1.5 – 10 m) tall. It grows natively in eastern Australia.
Creeping wattle (Acacia saligna)
Also called the Blue Leaf Wattle, the Creeping Wattle is a shrub-like tree with elongated leaves, clusters of bright yellow flowers, and long brown seed pods. Creeping Wattle trees are small shrubby, multi-stemmed trees growing around 6.5 to 19 ft. (2 – 6 m) tall.
Late flowering black wattle (Acacia concurrens)
This species, which grows in eastern Australia, has spikey, ball-shaped flowers that bloom in late winter or early spring.
Sweet wattle (Acacia suaveolens)
This large shrub grows in coastal Australia. Its creamy white flowers are extremely fragrant and attract many types of pollinators.
Sweet acacia (Acacia farnesiana)
Not to be confused with sweet wattle, this is a massive tree that can grow up to fifty feet tall. It grows natively in all of the world's inhabited continents. Its stems contain sharp thorns, which has earned it the nicknames thorn tree, needle bush, and huisache (which means "many thorns" in Mexico's Nahuatl language). Its leaves mimic that of the mimosa tree.
Flax-Leaf Wattle (Acacia linifolia)
The Flax Wattle is a small shrubby tree that grows between 5 and 13 ft. (1.5 – 4 m). This “white wattle” has evergreen linear leaves (phyllodes) that are up to 2” (5 cm) long. The long leafy stems also produce clusters of pale yellow or creamy-white flowers. Flax-Leaf Wattles bloom in summer and winter. Growing in USDA zones 9 through 11, the small trees thrive in full sun or partial shade.
Acacia koa (Acacia koa)
Acacia koa is an iconic wide-spreading shade tree that is native to the Hawaiian islands. Its beautifully figured wood makes it a valuable species for building everything from guitars to surfboards.
Kangaroo thorn (Acacia paradoxa)
The kangaroo thorn is an acacia shrub that can be used as a hedge. It spreads rapidly and is considered invasive in parts of Australia, South Africa, and California.
Sudan gum arabic (Senegalia senegal or Acacia senegal)
This plant goes by many common names including Sudan gum arabic tree, gum acacia, Kher, and Khor. It grows in Sub-Saharan Africa, India, and parts of the Middle East.
Camel thorn (Vachellia erioloba)
Camel thorn is a famous African acacia that is also known as a giraffe thorn due to its appeal to the long-necked herbivores. It produces light gray thorns and bright yellow blooms. Its seed pods attract a wide variety of animals including wild cows.
Preparing the Soil:
Acacia trees require well-drained soil, as the roots are delicate and susceptible to excess water. Like other legumes, acacias form symbiotic relationships with soil bacteria to fix atmospheric nitrogen, making them suitable for poor-quality sites. This is why they grow well in both arable fields and wastelands.
However, plowing the area before planting the trees will provide optimal rooting conditions and favor healthy development. Wherever they are located, acacias will need to receive full sun to thrive.
Planting Acacia Outdoors:
Regardless of their size, all acacia species display a vigorous growth in cultivation and should be planted in early spring, after the last frost has passed. Since some acacias are more frost-tolerant than others, the local hardiness zone should be considered before planting.
For best results, space acacias out according to the width the variety will reach at maturity. For example, one of the most popular varieties used for landscaping in southern and central Florida is Acacia farnesiana. It grows to a maximum spread of 30 feet (9 m). Therefore, the next tree should be planted at least 30 feet (9 m) apart.
When transplanting, each plant hole should be dug twice the depth of the pot. Thoroughly soak the hole with water before transplanting the acacia. Weekly watering is required until the new plant is fully established. It will take at least a year for a tree to become properly rooted in the soil.
Once the plant is established, follow normal watering, pruning, and weeding guidelines to encourage the best growth patterns. Acacias grow moderately quickly at five to seven feet (1.5 - 2.0 m) in just three to four years.
Planting Acacia Indoors:
The cultivation of acacia can done by seeding, grafting, or cutting. Acacia seed coats are hard and impervious to water; therefore, they require scarification or heat treatment to promote germination before sowing.
To heat treat seeds, boil the acacia seeds in water for up to 10 minutes. For scarification, carefully scratch the outer coat with sandpaper. After either process, let the seeds to soak in water for at least 24 hours. Afterwards, the acacia seeds should be swollen and ready to sow.
Place the seeds in a soft, moist medium (such as moss or wet tissue) until sprouts develop. After a couple of weeks, they can be transplanted into pots with moist seed mix. Never allow the roots to dry out.
In the initial stages, acacias seedlings should receive no more than six hours of light per day. Smaller acacia species may be permanently grown indoors in larger pots. Otherwise, potted plants can be transplanted outside during the following growing season. At that time, normal watering and spacing guidelines apply.
Though acacias are capable of withstanding dry conditions, extended periods of drought will adversely affect the species' growth, especially as a young tree or shrub. Conversely, overwatering Acacia spp. could lead to detrimental repercussions in the growing stages, including root rot.
Acacias survive best with deep, infrequent irrigation every one to two weeks. Once the tree is established, less water is needed, but irrigation of some sort is still important. Do not wait until a tree wilts or shows signs of water shortage before irrigating it.
Acacias respond well to a small amount of nitrogen fertilizer. However, it should not be added into the soil when initially planting the germinated seeds in pots or when planting the acacia outside.
The roots of young acacia trees are very delicate. In order to prevent and inhibit the growth of invasive weeds, hand-weed, hoe, or mulch around the acacia shrubs or trees as appropriate. Do not allow lawn to grow within a foot or two of trunks.
Depending on growing preferences, spraying herbicides may also be helpful, but it should not be necessary.
The main part of the acacia tree that is harvested is the sap from the bark, which known as gum arabic or acacia gum. This gum is generally harvested from Acacia senegal, since the species is praised for having superior properties.
A. senegal trees have to be under hydric stress before they produce gum. Having said this, it is important to decide the purpose of growing an acacia tree beforehand in order to provide the necessary conditions for gum harvesting or ornamental value.
The flowers of acacia are also collected to obtain a scented oil commonly used in perfumes. Most species of acacia are evergreen, but flowers bloom from November through February.
Acacia gum should be stored in a clean, cool, dry place. It does not deteriorate in storage as long as it is under favorable conditions. It will become hardened and darkened in color if wet.
This gum is soluble in water and foods, and it is often used as an emulsifier, stabilizer, and thickener. It is used in the confectionery industry for candies, jellies, glazes, and chewing gum. It has also been used as a stabilizer in soft drinks and beers. Acacia gum is also used by herbalists in the preparation of ointments.
Acacia flowers and foliage may be arranged and then left to dry naturally for later use in teas and other medicinal preparations.
Pruning and Propagation
It is important to prune acacia varieties to promote growth into well-shaped, mature trees. Some species may also be trained into multi-stemmed bushes.
It is best to prune established mature species minimally, removing dead, diseased, or damaged growth, as well as misplaced branches. Young plants may need more care to establish an attractive shape.
Do all pruning in mid-spring once the risk of frost has passed. This usually occurs around the month of April.
As a rule, acacia propagation tends to be by seed. Acacias produce big, distinctive seed pods that are hard to miss, and the seeds inside can usually be planted successfully. This method can be a problem, however, if you are looking to propagate a specific cultivar.
Some seeds from cultivars and hybrids will not necessarily grow true to type – you may plants seeds from a parent with a very specific flower color or growth pattern, and find its child doing something completely different.
Because of this, propagating acacia trees from cuttings is a safer bet if you’re dealing with a hybrid or specialized cultivar. Cuttings will always grow true to type, since they’re technically the same plant as their parent.
How to Propagate Acacia Trees
Propagating acacia trees from seed is quite easy. The large pods will turn brown and split open on the tree – if you keep an eye on them, you can harvest pods just before they split. In many species of acacia, the seeds have a hard coating on them that, in nature, is burned away naturally by bushfires. You can get rid of this coating by pouring boiling water over the seeds and allowing them to soak for 24 hours.
Check your species of seed to see exactly what kind of pre-treatment is needed. After this, the seeds can be planted in regular potting mix at a depth of about twice their thickness. They should germinate in 10 to 20 days.
Acacia reproduction from cuttings requires a 3- to 4-inch (7.5-10 cm.) long piece of new growth. The best time to do this is late summer or early autumn. Remove all but the top leaves from the cutting and sink it in good potting material.
Cuttings tend to root better in a warm, moist environment with indirect light. The success of cutting propagation varies widely depending upon the species.
Pests and Diseases Control
Pests and diseases can drastically reduce the yield of harvested parts of the acacia tree or shrub. Visual inspection of seed samples for the presence of pests may be combined with other quality control measures. In all matters, learning how to protect acacias is an essential part of growing them.
Mites and psyllids are of moderate importance as pests to Acacia spp., as they are threats to the trees' buds, shoots, flowers, leaves, and pods.
Acacia mites and psyllids can be prevented by removing and destroying the infested parts; bud and graft material may contain mites as well and need to be treated chemically with insecticides.
Other common Acacia spp. pests include phyllode spotting mirid bugs and macadamia nutborers. To get rid of them, it is necessary to follow the above procedure.
Benefits of Acacia
Relieves pain and irritation
Acacia gum has a naturally sticky texture. Materials with this property are often used to reduce irritation and inflammation. The gum has been shown to be especially effective in easing stomach or throat discomfort.
Helps wound healing
Acacia is often used in topical treatments to help wounds heal. Doctors, scientists, and researchers believe that this effect may be due to some of its chemicals, such as alkaloids, glycosides, and flavonoids. In one study, a species of acacia known as Acacia caesia was tested on rats as part of a topical wound treatment. It led to quicker wound healing than the standard treatment.
Another animal study suggested that acacia may also help heal ulcers.
Soothes coughs and sore throats
Because it’s known to relieve irritation and inflammation, acacia gum can also help control coughs. The properties of acacia gum allow it to be used in solutions to coat your throat and protect the mucus in your throat from irritation. Using acacia for coughs can keep your throat from becoming sore as well as ease or prevent symptoms, including losing your voice.
Restricts blood loss
The Acacia greggii plant, found in the United States and Mexico, can be used to help stop blood flow in gashes, wounds, and other surface cuts. Pouring an acacia-infused tea on cuts is an especially effective remedy. This can be helpful for stopping heavy bleeding and washing bacteria from the cut.
Acacia is also known for reducing weight as it contains rich fiber and eating a diet rich in fiber helps you stay full for longer. It is obvious that when you feel satisfied and full with stomach, you are less likely to snack and this in turn help you in reducing your weight or treating obesity.
Acacia is also known to have a fair role in lowering cholesterol. By adding Acacia gum to your diet you can lower your cholesterol levels significantly.
Detoxifying and Cleansing Agent for the Body
It is also known that Acacia is used as an ingredient in total body detox or cleansing procedures. Acacia is important in cleansing the body because of the fiber contents present in it.
Enhancing the Immune System
Body’s immune system is also improved by taking Acacia extract. Research studies have shown that Acacia extract has increased the WBC count in mice, making their immune system stronger and more functional. It is also known that Acacia extract reduces the side effects of chemotherapy. This in turn may help the cancer patients stay healthier and stronger throughout their treatment.
Though there are no strict proofs about Acacia being helpful in treating diabetes; some claim that Acacia supplements can aid in controlling your blood sugar level. It is however known that foods rich in dietary fiber helps in regulating blood sugar in patients with type 2 diabetes. Thus by taking foods with added Acacia may boost their daily fiber and in turn aid in regulating blood sugar level.
Dental Health Benefits
Acacia may help you keep brighter smile and appropriate dental health. In fact an extract of one type of Acacia tree is added to toothpaste for more benefits, especially in lowering risk of gingivitis and maintaining a daily oral hygiene. Even early research has suggested that Acacia gum having antibacterial properties aid control harmful bacteria in the mouth that leads to various gum diseases. Apart from this, studies have also concluded that chewing gum made with Acacia was more beneficial in reducing plaque for 7 days when compared with the regular toothpaste.
Acacia trees and shrubs are prized for their beauty, but they also play an important role in various industries.
1. Tanning: Thanks to the intense tannins in acacia wood, the species is used in tanning and various forms of leather work.
2. Woodworking: Some luthiers seek out koa wood for constructing guitars. The wood can also be found in surfboards and canoes.
3. Dyes: The seeds of coastal acacia can be used to make green dye while its flowers can be used for yellow dye.
4. Gums: Acacia gum arabic is used as a food additive, as an adhesive, and as a cosmetic.
5. Perfume: As flowering plants, acacias have been used in perfume manufacture. This is particularly true of the fragrant golden wattle species.