- Mesquite trees are small trees or shrubs in the pea family (Fabaceae) -Very common in southern Arizona, mesquites grow in dry stream beds, washes, flood plains, rivers, grasslands, and hillsides [This particular tree is in Agua Caliente Park ... see if you can find it when you're there. But this one is NOT the BIG ONE!! There is another one in the park that is really special! --Jim]