Common Name(s): Prickley Acacia, Gum Acacia, Gum Arabic

Synonym(s):

Family: Fabaceae

Native To: Northern to sub-Saharan Africa

Native Habitat: Acacia nilotica grows in a variety of large woodland areas and above seasonal drainages in grasslands of sub-Saharan Africa.

Growth Habit: A. nilotica is a semi-deciduous, slow growing tree that can reach up to 30 ft. in height, although it’s normally much shorter. The moderately dense crown is flattened and wide, if there’s enough space. Branches are horizontal to drooping.

Flowering: Flowering is during winter, triggered by low temperatures and possibly dryer conditions in habitat. Pods then form as the spring/summer weather warms and becomes wetter.

Distinguishing Characteristics: The bark, in mature trees, is dark brown to blackish grey in color, with deep vertical fissures. Young branches are reddish brown to grey in color and may be covered in small hairs. Spines occur in pairs at the nodes on most branches, are white to light reddish purple, 1-3 inches long, and curve downward or backward. The delicate leaves grow to 3 inches long. They are twice compound with 5 to 11 feather-like pairs of pinnae, holding up to 25 pairs of bright green elliptic leaflets. The leaf stalks are relatively heavy in weight. Small glands found at the base of the petiole and/or upper pinnae can be almost unnoticeable. Flowers are yellow pompons – typical Acacia flowers, but nearly 1 inch in diameter.

Natural History and Cultivation Notes: Acacia is from the Greek word akis which means sharp point, while nilotica refers to its establishment along the Nile River. However, it is now common in most countries south of the desert, through the central tropical zone. The sub species adstringens is found in the western half of the range.

With adequate moisture, pod and seed production is reported to be rapid and heavy – but the seeds don’t remain viable past a year or two, especially in Africa where they are often destroyed by small herbivores. Seeds are spread by ruminants – and the species is considered weedy in Australia and the Indian subcontinent where it is not kept in check.

Ethnobotany: In Sudan, the hard wood of Gum Arabic is used for construction. It is reddish in color and can be used for firewood, fencing or house posts. The red color is a source of dye for some African groups. The gum (for which the tree is named) exudes through the bark and is used for glue and medicine.

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