Vachellia macracantha und Vachellia tortuosa are widespread in the Americas and they are quite similar. Because of their intraspecific variations it is not easy to distinguish between them.
One of the differences are the laterally flattened spines of up to 10 cm in V. macracantha. V. tortuosa has shorter cylindrical spines.
In addition the fruit of V.tortuosa has a small stipe to 5mm long and the species is distributed at relatively low altitudes.
See also Vachellia macracantha and Vachellia tortuosa in Venezuela