Physocarpus opulifolius, known as common ninebark, Eastern ninebark, Atlantic ninebark, or simply ninebark, is a species of flowering plant in the rose family Rosaceae, native to eastern North America.
Physocarpus opulifolius, commonly called ninebark, is an upright, spreading, somewhat coarse, deciduous, Missouri-native shrub which is closely related to genus Spiraea. Grows 5-9’ tall (less frequently to 10’). Noted for its exfoliating bark (on mature branches) which peels in strips to reveal several layers of reddish to light brown inner bark (hence the common name of ninebark). Bark provides winter interest, but is usually hidden by the foliage during the growing season. Features small pink or white, five-petaled flowers appearing in dense, flat, rounded, 1-2” diameter, spirea-like clusters (corymbs) in late spring. Flowers give way to drooping clusters of reddish fruit (inflated seed capsules). Ovate to rounded, usually 3-5 lobed leaves (to 4” long) are dull green in summer changing to an undistinguished yellow in fall.