Vachellia karroo is common around the Magaliesberg, growing on rocky outcrops, along streambanks or on grassy plains around the foot of the mountains. Often only reaching shrub size in multi-stemmed form, a tall, single, erect stem may sometimes be grown, the canopy wide in maturity when standing alone.

Blooming during the hotter months, the generous stem-tip inflorescences attract many insects. This is achieved by both the appearance of the bright, yellow flower spheres and their strong sweet fragrance.

Leaves and fruit pods feed browser animals that live here. The flowers feed the bees and other insects that visit and pollinate. Nitrogen-fixing bacteria in the roots of these trees fertilise the soil, thus feeding the grasses near them that in turn feed the grazing animals.

People use the wood for tool handles. Before cars reduced animal contributions to human transportation, this wood was also used for cart and wagon wheels, spokes and yokes.

Leather can be tanned using the bark. Summer Christmas trees of the southern hemisphere differ from the Tannenbäume of Europe, sometimes including the sweet thorn (Grant, et al, 2001).