Vachellia collinsii is a species of flowering plant. It grows in secondary succession in seasonally dry ecosystems in southern Central America, where it exhibits a symbiotic relationship with several species of ant (Pseudomyrmex spinicola, Pseudomyrmex ferruginea). The ant-Vachellia system involving this species has been studied by ecologists like Daniel Janzen in Palo Verde National Park and Santa Rosa National Park, both in Guanacaste Province, Costa Rica. The ants chew holes in the tips of the hollow stipular thorns, known as domatia, so that they can enter, and create their colony inside. A single ant colony may span several V. collinsii trees.