Evolution
Solanum aculeastrum flowers.
Most members of the genus Solanum have evolved in Central and South America (Knapp 2002).
Recent molecular research suggests that spiny solanums have evolved once, and within spiny solanums there was one radiation from Central and South America to Africa and Asia (Levin et al. 2006, Weese and Bohs 2007).
Among the group in Africa and Asia S. aculeastrum is most closely related to S. phoxocarpum, and the dissimilar S. coagulans from northern Kenya and Ethiopia (Levin et al. 2006).