Acacia willardiana

Acacia is indigenous to warm regions like Mexico and Australia. They attract birds and work well in multiple climates. They are generally used in landscaping. Acacia seeds are often used for seasoning food and drinks, and are listed as ingredients in Barq's root beer and Altoids mints. The species Bullhorn acacia lacks the bitter alkaloids usually located in the leaves that defend against insects and animals. Bullhorn acacia ants fulfill that role. They lives in its hollowed out thorns at the base of their leaves and protect the tree and in exchange live off the protein rich nodules (Beltian bodies) and nectar from the glands on its leaf stalk. There is no other known function of these Beltian bodies than to feed the ants. The aggressive ants release an alarm pheromone that livestock smell and avoid. The ants will also "prune" seedlings around it to prevent them from block out sunlight, which the Acacia's need to survive.