Vachellia

Vachellia is a genus of flowering plants in the legume family Fabaceae, subfamily Mimosoideae. It comprises trees and shrubs, many with paired spines, that are native to tropical and subtropical regions of Africa, Asia, the Americas, and the Middle East. The genus was established in the 2000s as part of a taxonomic split of Acacia; African and American species formerly placed in Acacia were reassigned to Vachellia, while many Australian species remained in Acacia or were moved to related genera such as Senegalia.

Description and biology: Vachellia species typically have bipinnate leaves and thorns or spines, though some are spineless. They produce small, dense inflorescences of yellow flowers typical of mimosoid legumes, followed by flat or slightly curved seed pods containing seeds. The plants are usually adapted to dry or seasonally dry habitats and some species are well suited to poor or disturbed soils.

Distribution and ecology: Vachellia species occur in savannas, woodlands, thornbush, and scrub across tropical and subtropical regions. They form symbiotic relationships with nitrogen-fixing bacteria in root nodules, contributing to soil fertility. They provide browse for livestock and wildlife, and several species are used in agroforestry, for shade, fencing, or timber.

Notable species: Vachellia nilotica, Vachellia farnesiana, Vachellia erioloba, Vachellia tortilis, and Vachellia karroo are among the widely known members. Taxonomic changes continue to reflect phylogenetic relationships within the Acacia group.