[7] Most botanists prefer to classify Mahonia as a part of Berberis[8][9][10][11] because several species in both genera are able to hybridize, and because there are no consistent morphological differences between the two groups other than the leaf pinnation (Berberis sensu stricto appear to have simple leaves, but these are in reality compound with a single leaflet and are termed "unifoliolate"; additionally their branched spines are modified compound leaves[12]).

Several species are popular garden shrubs, grown for their ornamental, often spiny, evergreen foliage, yellow (or rarely red) flowers in autumn, winter and early spring, and blue-black berries.

[15] The plants contain berberine, a compound found in many Berberis and Mahonia species which causes vomiting, lowered blood pressure, reduced heart rate, lethargy, and other ill effects when consumed.

[15] The genus name, Mahonia, derives from Bernard McMahon, one of the stewards of the plant collections from the Lewis and Clark Expedition.

[16][17] Some Mahonia species serve as alternate hosts for the cereal disease stem rust (Puccinia graminis).