n 1  cap  :  a large genus of American shrubs (family Berberidaceae) that typically have prickly stems and yellow flowers succeeded by red berries, that in some classifications include members of the genus Mahonia, and that with Mahonia comprises the barberries  2  :  the dried rhizome and roots of some barberries of the genus Mahonia (esp. M. aquifolium) that contain a number of alkaloids (as berberine and berbamine) .
 
 
 
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