Physocarpus are deciduous shrubs with alternately arranged leaves. The leaves are palmate with 3 to 7 lobes and often toothed edges. The inflorescence is a cluster of bell-shaped flowers with 5 rounded white or pink petals and many stamens. The fruit is a flat or inflated dehiscent follicle. The genus name Physocarpus comes from the Greek for "bladder fruit", referring to the inflated fruits of some species. The common name ninebark refers to the peeling bark of mature branches, which comes away in strips. Physocarpus opulifolius is cultivated as an ornamental plant. Several cultivars have been bred, particularly for foliage of varying colors, including 'Dart's Gold' and 'Luteus', which have yellowish leaves, and 'Monlo' and 'Seward', which have reddish purple foliage.