What’s in a Name: Disputed Nomenclature for Acacia Trees

Carl Linnaeus, whose self-chosen epitaph reads, “God Created, Linnaeus arranged” was a major mover in the creation scientific names used today for trees and other sorts of plants, as well as animals. Often, scientific names are what help lay-people, including those running tree nurseries and farms, use to determine precisely what tree they are ordering from other areas or that they are growing in their own facilities.

Determining type of tree can be extremely important. For example, brachychiton rupestris, popularly known as Queensland Bottle Tree, is completely legal to grow or sell providing the seed or young trees is obtained from a licensed source such as Designer Trees. However the baobab, Adansonia gregorii, also known as “bottle tree”, is on the endangered list and certainly should not be cut down or destroyed, nor is it generally available for growing by individuals. The scientific names for these two “bottle trees” helps growers to differentiate between the two tree types and helps to keep everyone out of trouble.


Acacia: a Name Under Debate

But what happens when the scientists cannot decide what to call a species? That is what has happened with acacia trees.

Trees called acacia grow naturally in Africa, Australia, and South America. Acacias are grown under cultivation and as ornamentals in many other areas. The confusion over the name begins with a Greek physiscian named Discorides who used parts of a plant he called Akakia to create medicines.

“Akakia” simply means “spiny”. Today, the scientific name for Discorides plant is vachellia nilotica. Why the name change? The answer lies in human psychology and the tendency to call similar plants by a familiar name. As people from the European and Mediterranean parts of the world sailed their ships to other regions, they saw trees that looked a lot like their beloved acacia trees. Before too many centuries had passed, there were trees in Africa, South America, and Australia that were called acacia. In Australia, these trees are also known as “Wattles.”

There are 1350 different trees and bushes called acacia growing throughout the world, 1000 of which are found in Australia. Perhaps the most heartily contested use of “acacia” as a name for trees has been between Australia, which has the greatest number of acacia types and Africa, which includes the “akakia” originally used by Discorides. (It is perhaps a sobering thought to realize that the Greek physician and philosopher only lives on in his writings, whereas there are living scions of the tree from which he made medicines still available in the world today.) So how did this polite, scientific brangle over nomenclature fall out?

As you can see from the paragraph above, Discorides “akakia” is now called vachellia nilotica. It is the tree from which resin is gathered to make gum Arabic, an ingredient that has shown up in many food, medicine and other preparations down through the ages. In its native habitat, it is used for food and medicine. In the United States, it is considered to be a noxious weed for its thorns and its spreading growth habit. It is a persistent grower in most habitats. It is also known as the gum Arabic tree, mimosa, thorny mimosa, Egyptian Acacia, and thorny Acacia.

This renaming process has continued and has become an even hotter topic as scientists have learned to apply DNA analysis to plants. In the 1980s, Leslie Pedley, an Australian botanist, introduced the term “Racosperma”, which covered about 900 of the 1000 Australia “acacias”. Even so, in 2011, the International Botanical Congress voted to allow Australian species to retain the “acacia” nomenclature, and to rename the African species.  Thus, we have names such as racosperma melanoxylon for the Australian blackwood tree, and acacia pycnantha for the golden wattle.


Revisiting Importance of Names

Why are these names so important? Scientific naming helps sort out specific plants and is important to the study of plant populations. Here, almost at the eleventh hour and fifty-ninth minute, humans are discovering that reducing plant diversity reduces animal diversity, which can, in turn, reduce humanity’s chances at survival. As we see above, distinguishing between the Queensland bottle tree and the baobab or boab sort of bottle tree helps differentiate between a non-threatened species and one that is on the threatened list.


Are There Endangered Acacia?

Yes, there are endangered acacia. For example, the Western Wheatbelt Acacia, acacia brachypoda, is on the threatened list.  It is a low-growing shrub, measuring between 3 feet and ten feet tall, characterized by the fluffy leaves and golden blossom balls that can be seen on many acacias. It has a relatively small native growing area on the edge of Australia’s wheatbelt.

  1. brachypoda is a good demonstration of the scientific name game. Botanist Bruce Maslin first classified it as acacia in 1990. Leslie Pedley classified it as Racosperma in 2003, then it was changed back in 2006.

Meanwhile, the shrubby small tree continues to exist, especially in areas near streams and riverbanks where it can get its toes into the water sources that it needs, completely oblivious of the naming business, but still under pressure form surrounding farms and agricultural practices.


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