In southern Central America, where there are seasonally dry ecosystems, this tree grows in secondary succession, preferring Savanna-like climates.

[2] On the petioles, are green bumps called extrafloral nectaries that create sugar for symbiotic ants.

While most tree species typically have auxin that grow downward, suppressing branch growth on the sides, this is not the case for Vachellia Collinsii, as it lacks a strong apical meristem.

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.

Medium sized herbivores are often deterred by the thorns alone, but the ants help protect the trees from other potentially threatening animals.

This provides V. collinsii with valuable space and unimpacted access to sunlight, allowing the trees to thrive.

Vachellia collinsii also provides the ants with sugar-rich nectar from extrafloral nectaries located at the leaf petiole.

[citation needed] The symbiotic ants living on this tree become alarmed at tissue disruption of the plant’s leaves by herbivores like the scarab, Pelidnota punctulate.

Diving deeper into why the acacia collinsii produce traits of the “swollen thorn syndrome,” the mechanism and pathways are still unknown but there have been experiments and strong evidence related to a change in gene expression of miR156/miR157 and SPL transcription factors, in different environmental conditions.

The production of food bodies that are high in proteins and lipids as well as extrafloral nectaries is very costly so the plant must have some indication of when to start producing those traits.

[8] When put in low light conditions, there is higher miR156/miR157 as well as a delay in swollen thorn syndrome traits.

The other way around is also true in that when put in well lit conditions such as the natural environment, there is a low expression of miR156/miR157 genes when the plant is producing extrafloral nectaries, swollen stipules, and beltian bodies.