The Pacific ninebark (Physocarpus capitatus) belongs to Rosaceae (the Rose family). It is a small deciduous tree that is native to the western United States. This tree grows up to 3 m in height, and the leaves have maple-like, palmate lobed and arranged in alternate. The many white flowers bloom in the corymbs atop of twigs from May to June. The genus name comes from the appearance of the bark, which is flaky, peeling away in many layers.