BULL'S HORN ACACIA

Bull's-horn Acacia, "Subin" in Maya, and ACACIA COLLINSII in Latin, is a common bush or tree here. This species provides a textbook example of mutualism. To see what I mean, take a look at my picture at the right.

That picture shows ants on one of the thorns. Those thorns are hollow and the ants live inside them, entering through ant-size holes near the thorns' tips. Notice those little green-apple-like things on the purple leaf petioles. Those are glands secreting sweet, energy-rich nectar the ants feed on. Finally, notice the yellow to yellow-orange items on some of the lower leaflets. These are Beltian bodies, which are protein-rich structures produced at the ends of some leaflets, and the ants eat them, too.

You can't see yet one more element of the mutualistic relationship between ant and tree. You learn about it fast, however, if you touch any part of the plant: Ants swarm over your hand, biting.

Finally, I've read that the ants clear away other plants from around the acacia, and that seemed to be the case with this particular plant.

So, acacia, ants and their tendency to bite, Beltian bodies, nectar glands, weed removal... All right there in front of me along a path I take every day, right on the hacienda grounds. I always show this to the tourists and they seem to agree with me that this is just about as impressive as anything else here.