When you hear the word Acacia, do you think of umbrella-shaped trees in the African Savanna? Or maybe shrubs in the dry American Southwest? Or even the Australian outback? Acacias are a group of trees and shrubs with over 1,000 species and a wide range! Let’s take a quick tour of the most interesting facts about these trees!
Where do they grow?
Acacias are well adapted to deserts and tropical areas. Therefore, they have a wide distribution and are native to Australia, South Africa, the Southwestern United States, and South and Central America. Some people plant species of these trees for their attractive yellow blooms. Because they are so diverse and fast-growing, some of these species have become invasive.
What do they look like?
Though acacias are quite diverse, they share some common characteristics. The genus Acacia is a member of the pea family (Fabaceae). This family shares the distinctive seed pods that peas, acacias and other legumes grow.
They often have many small oval leaves (called pinnate leaves) along their “leaflets.” This gives them the appearance of a double-sided comb. These leaflets attach to the main stem by a leaf stalk called a leaf petiole.
Sharp, threatening thorns protect acacias precious leaves from herbivorous (plant-eating) animals. They need these thorns in the dry environments where they grow. When it rarely rains, losing the water in your leaves can be a death sentence. This is a common strategy for desert plants.
Acacias can be shrubs or trees of all sizes. However, the large, umbrella-shaped acacias of the African Savanna are an easily recognizable image. Other acacias can be low growing groundcover or small shrubs.
Do you think you have spotted a species of acacia in your yard or on a hike? Use the PlantSnap app to identify it!
What are some examples of types of acacia tree?
Acacia senegal – Gum Arabic, Senegal Gum, Sudan Gum Arabic
This plant produces gum arabic. This resinous substance has many applications in pharmaceuticals, food science, and traditional medicine.
Acacia pycnantha – Golden wattle
This species of acacia is Australia’s national flower! The yellow globes of its bloom are actually many small flowers.
Acacia genistifolia – Spreading wattle
This low growing acacia grows white flowers in beautiful orbs.
What are acacia trees used for?
A wide variety of products use gum arabic. It comes from multiple species of acacia tree and has a wide variety of applications. These include pharmaceuticals, soda, newspaper ink and even as food. The most common sources of this product is the species Acacia senegal. Many species of acacia including Acacia richardsii produce this product. Gum arabic has historically been an important part of the Sudanese economy. Currently, climate change is threatening this industry by decreasing acacias sap productions.
Catechu and Tannin dyes
Acacia trees including Acacia catechu can dye fabrics a dark color. This is due to extracts containing tannins and catechins. These dyes both color and preserve cloths. It is also used much like gum arabic as an emulsifier.
One of the most common uses of acacia is for its wood. This is because it is an extremely durable wood. It also resists water damage and scratching. Because these trees are so fast growing, harvesting acacia wood is sustainable. These features make acacia very popular for woodworking.
Thorny homes for ants
Acacias have a surprising tenant on their branches! Many species of acacia have symbiotic (mutually beneficial) relationships with species of ants. The plants provide ants with food and a home in their thorns. In exchange, the ants kill bacteria, leaf-eating insects, and competing plants.
Some species of acacia form a tasty treat on their seeds. Therefore, they convince ants to carry the seeds deep into their colony. Consequently, planting the next generation of acacias! The ploy may go deeper than just a good ant snack. Research shows the plants may use oleic acid to stimulate corpse carrying behavior by the ants. As a result, the ants carry the bulky seeds home with them.
Read more about how ants and plants ended up working so closely together.
The tall acacia trees of Africa provide an important food source to Giraffes. The silhouette of a giraffe eating the leaves of an umbrella-shaped acacia is a classic image. However, Giraffes are now facing the threat of extinction. This essential food source is becoming increasingly important to the ecology of the African savanna.
Humans have also begun using acacia trees as food. There are claims of numerous health benefits of this high fiber food. Eating too much acacia has the potential to make some people sick. So be sure to consult with your doctor before introducing acacia products into your diet!
Acacias provide many benefits to natural ecosystems. However, many species of acacia have begun to invade new ecosystems. This is due to their fast growth, spines, and attractive flowers.
Many species become invasive after introduction as attractive landscaping plants. For example, Acacia confusa is an example that was introduced to Hawaii for its pretty yellow flowers.
Other species have introduced for their economic value. For instance, Acacia maernsii, or black wattle, is an example that was introduced from Australia to Africa. It was introduced for commercial production of resins, timber, and medicine. Since then, the fast-growing plant has quickly become a weed. It replaces native grasses and decreases water availability.
Acacias are a diverse genus with many interesting and useful species. Whether you are a human, ant, or a giraffe, you will have no trouble falling in love with these beautiful trees.