The US has ten genera and 32 species in the berberidaceae (barberry) family, characterized by large leaves (often with spiny margins), spiny stems, and flowers with 4, 5 or 6 sepals, the same number of petals, and 4 to 18 stamens (arranged in two concentric rings). Plants can be trees, shrubs or herbs. Flowers may be single or part of clusters, elongated or spherical.