Acacia, commonly known as wattles or acacias, is a genus of about 1,084 species of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa, South America and Australasia, but is now reserved for species mainly from Australia, with others from New Guinea, Southeast Asia and the Indian Ocean. The genus name is Neo-Latin, borrowed from the Greek ἀκακία, a term used in antiquity to describe a preparation extracted from Vachellia nilotica, the original type species.

The Mimosoideae are a traditional subfamily of trees, herbs, lianas, and shrubs in the pea family (Fabaceae) that mostly grow in tropical and subtropical climates. They are typically characterized by having radially symmetric flowers, with petals that are twice divided (valvate) in bud and with numerous showy, prominent stamens.