The Bullhorn Acacia
By Susana Cortázar
A unique feature of this tree is that colonies of stinging ants make their home in the hollowed-out thorns and are true defenders of the tree – fending off insects, curious mammals and epiphytic vines! Why does this happen? Because the bullhorn acacia lacks alkaloids normally found on the leaves of other trees which act as a deterrent to insect and other animal infestation. In the case of the bullhorn acacia, the ants “take over the job” of the alkaloids. In return – mutualism – the bullhorn acacia provides the ants with protein lipids, which are found as little white spots on the acacia’s leaves, and nutrition in the form of a nectar rich in carbohydrates from glands on the tree’s leaf stalk.
Other interesting facts about the bullhorn acacia, aside from providing food and shelter for the ants, is that the tree’s thorns are sometimes strung together to make necklaces and belts. In some Central American countries, the thorns are used to make the legs for small ballerina dolls which are worn as pins by the locals.