Any of the approximately 800 species of trees and shrubs that make up the genus Acacia, in the family Fabaceae. Acacias are native to tropical and subtropical regions of the world, particularly Australia and Africa. Sweet acacia (A. farnesiana) is native to the southwestern U.S. Acacias have distinctive, finely divided leaflets, and their leafstalks may bear thorns or sharp spines at their base. Their small, often fragrant, yellow or white flowers have many stamens apiece, giving each a fuzzy appearance. On the plains of southern and eastern Africa, acacias are common features of the landscape. Several species are important economically, yielding substances such as gum arabic and tannin, as well as valuable timber.