The umbrella thorn or in Afrikaans haak-en-steek or krulpeul (curl pod), as Vachellia tortilis subps. heteracantha is commonly known, can grow to a large tree in habitat. The subspecies distribution lies in the northern parts of South Africa and more widely in southern Africa.

Tortilis means twisted, referring to the convoluted shape of the fruit pods. Depending on winter temperatures of the region or severity of a season, this tree may remain evergreen.

As the umbrella thorn gains stature, the crown becomes flat with slightly drooping edges, displaying bare stems (or stem) lower down. This is the tree-shape made famous by the artist Pierneef (Coates Palgrave, 2002).