African Acacias

There are more than a hundred species of African Acacia.  They come in many shapes and sizes: from small bushy shrubs to large flat-topped trees.  

What all Acacias have in common...

Why were they called Acacias?

Botanists put all these trees into the botanical group called Acacia because they share many features.  They are all  ‘armed’ with thorns or hooks. They all have seeds in pods. They all have fuzzy-looking flowers (with long stamens and small petals) and most have feather-like (bi-pinnate) leaves. Grouping trees together helps us to understand their place in the ‘family tree’ of living things, giving us clues about how they evolved and their special characteristics: for example their medicinal properties or their ability to grow in a particular place.  

Why have their names changed?

The Acacia group was very big – more than a thousand trees spread across the world. As botanists developed better ways to study trees, using biochemical and molecular tools, they decided it would be useful to divide the Acacias into smaller, more similar groups.  The African acacia trees were placed in the new groups based on their shape (morphology and anatomy) and on their biochemical attributes.

Most Acacias (almost 1000) come from Australia.  These got to keep the group name ‘Acacia’. The African Acacias were put into three new groups. The second name of the tree remains the same.  So, for example, Acacia abyssinica became Vachellia abyssinica.

Meet the Vachellias, Senegalias and Faidherbia!

Vachellia abyssinica (Flat-top acacia)

Other names:Mugaa (Kikuyu), Ogongo (Luo), Munyenya (Luhya).

The genus is named after the 18th century English plant collector the Reverend George Harvey Vachell. 

This tree is used for fuel, posts and shade. Its resin is gummy and edible.


Read about Vachellia xanthophloea, the Fever Tree here

These Senegalia senegal trees are in Borana ranch in Laikipia.  Thank you Teddy Kinyanjui for this photo.

Senegalia senegal (Gum arabic tree)

Other names: Kikwata (Swahili), Kikole (Kamba), Gabra (Idaado)

This genus is named after the country of origin of many of the trees in this group.

Senegalia senegal grows in dry areas all over Kenya and is used for firewood, tools, posts, fodder for livestock and forage for bees. This tree also has medicinal properties and is a source of gum arabic an ingredient in sodas, chewing gum, paints and much more.

Faidherbia albida (Apple-ring acacia)

Other names: Olasiti (Maasai), Sangale (Pokot), Edurokoit (Turkana).

The generic name Faidherbia is named for the 19th century French governnor of Senegal Louis Faidherbe.   'Albida' means 'white' and refers to the tree's pale trunk.

This tree is very useful for farmers in dry areas as it grows leaves and pods in the dry season providing food for livestock.  In the rainy season, it stops growing and drops its leaves, providing light and fertiliser for the growing crops.

What did the scientists find?

In his article ‘Reclassifying the African Acacia’ Joel Lewis says that the genetic data show that the African Acacias actually come from two very different legume lineages which separated about 30 million years ago.  The split occurred when species of Vachellia moved into open habitats, while Senegalia remained in the ancestral forests.  About 10 million years ago the Senegalia also moved out into open savanna like habitats.

Do you know about the Great Green Wall?

The Great Green wall is a project to create a new Wonder of the World by planting trees, mainly Acacias right across the continent of Africa.

Click on the picture below to find out more.

The Great Green Wall of the Sahara and Sahel.docx

This article was kindly shared with us by Peter Miles, an Australian Environmental scientist.  Click here to read his story about micro and macro organisms living in the soil.  You can also visit his website here.

This printable fact sheet (great for schools and wildlife clubs) is available free of charge.  Email Tree Safari if you would like us to send you one.