Common Name: 
This genus has numerous species of evergreen and deciduous shrubs with spiny stems and yellow wood.  Leaves are simple (but now also compound, see below) with their margins often armed with spines.  Flowers are yellow to dark orange-red, borne singly or in clusters, 6 sepals and petals in 2 ranks.  Fruits ovoid to cylindrical, yellow, red or black-blue.   Botanists have broadened the genus to include the Mahonia, which have compound leaves.  Therefore, in the botanical literature Oregon Grape, Mahonia aquifolium, is known as Berberis aquifolium.   However, in commercial horticulture it is still known, and sold, as Mahonia aquifolium.  It and other Mahonia are listed under the traditional genus name in this web site.
Berberis: from berberys, the Arabic name for the fruit.