The thorns are the first thing you notice, fat and paired and curved like a bull’s horns. The second thing you notice is the ants, if you have touched the plant, because by then they are on you and stinging.
Where you’ll see it
Dry forest, scrub and pasture edges across Guanacaste. It is common and easy to identify once you know the thorns.
What to know
The acacia and the ants have a deal. The tree grows the hollow thorns as housing, produces sugary nectar from glands on the leaf stalks, and grows tiny protein-rich packets on the leaf tips to feed the colony. The ants live in the thorns and attack everything: insects, browsing animals, a hand on a branch. They even prune back other plants that touch their tree. Rufous-naped wrens nest inside this defence. You should not test it.
