Many acacias grow in tropical and subtropical regions of Australia, Africa, and the Americas. More than 30 species, most of them shrubs, grow in the United States. They are most common from Texas to California. Catclaw acacia The flowers of most acacias are either yellow or white and grow in round or long clusters.
Many species have compound leaves consisting of numerous leaflets.
In some species, the leaves grow from wide, flat leafstalks. Other species of acacias lack true leaves and have only the leafstalks. Certain species, including the catclaw acacia of the southwestern United States and the bullhorn acacia of Mexico, have sharp spines. The bullhorn acacia has large, paired hornlike spines that are partly hollow and often inhabited by ferocious ants. These ants attack any other animal that invades the tree.