There are approximately 800 species of Acacia. Around 600 of those species are found in Australia and Pacific islands. The large genus is in the pea family and is mainly made up of tropical and subtropical trees native to Africa and Australia, with a few in the Americas. In Australia they are called Wattles. Acacias are mainly known for their leaves, which grow in small, divided leaflets and have a fern-like appearance. Some Australian and Pacific species have suppressed or no leaflets and their leafstalks are flattened to perform the function of leaves. They are also notable because of their small fragrant flowers which grow in cylindrical clusters. The blooms are typically yellow or sometimes white. Acacias are strongly associated with savannah and plains regions of Africa, where they grow in abundance.
In the 1700s, Acacias were highly valued for their wood, used in ship building. Today they are still of economic importance. Several of the Australian species are also a source of tannin, such as the Golden Wattle (Acacia pycnantha), Green Wattle (Acacia ecurrens), and Silver Wattle (Acacia dealbata). Still more species produce valuable timber, like the Australian Blackwood (Acacia melanoxylon). A great deal of the Australian species have been introduced around the world and they are grown as small trees for their showy flowers.
Many Acacia trees have relatively short lifespans for trees, only living 15 to 30 years. They do grow very rapidly though and some species can grow as tall as 40 feet (12.2 meters). Some of the most popular general types of Acacia are flat-topped, swollen-thorn, koa and flowering acacia. The flat-topped Acacias are the ones recognized from African plains. Swollen-thorn Acacias can be found in Central America and these species of tree often form symbiotic relationships with ants. Koa Acacia are native to Hawaii and they produce a popular dark hardwood. Flowering Acacia are further divided into two groups: the baileyanas and the farnesiana. Baileyanas are the species that have yellow flowers, while the latter more closely resembles a spiny shrub than a tree.
Acacias are prone to anthracnose, a leaf infection. It is caused by a fungus that quickly moves into the stems and can destroy the entire tree. Goat moths will also destroy the bark of the trunks. Mites and aphids will also feed on Acacias. Aside from these issues, Acacias are easily grown in almost any warm climate. They thrive in hotter, drier regions, but will tolerate moisture so long as they are placed in well -raining soil. Be careful not to overwater any Acacia, and some of the species need minimal pruning. Their main requirement is direct sunlight.