Arboretum: Cotinus coggygria, common smoketree
Cotinus coggygria, the common smoketree, is not really a tree, but a multi-stemmed shrub that can reach to over 15 feet and the stature of a small tree. The rounded leaves are bluish green to purplish red and the plant grows with a loose, open habit. The range of colors in the foliage start to intensify as summer comes to a close and the air gets cooler and the days shorter. At the same time, the somewhat insignificant flowers of spring give way to smoky pink panicles at the ends of the branches that appear light and airy, similar to ornamental grass seedheads.
Common smoketree hails from southern Europe to central China and is adaptable to a range of soils. It prefers sunny sites, and can be used in a large container or as an accent in the back of a perennial bed or in a shrub border. The plant can be cut to the ground in late winter to control growth and also take advantage of the strong color of emerging shoots.
Cotinus obovatus, American smoketree, is very similar to the Eurasian species. It grows upright to 20 or 30 feet. It’s a round or oval-headed plant with bluish to dark green leaves that turn a glowing mixture of orange, amber, red and purple in the fall.
The bark is gray to grayish brown. Its greenish flowers appear in mid-spring and form 6 to 10-inch long panicles. Cotinus obovatus is found naturally in limestone areas of Tennessee, Alabama and Oklahoma, but will thrive in our area if given enough sun and a moist soil. It was nearly wiped out in the 19th century by settlers who used the orangey heartwood to produce a yellow dye. A specimen of this native plant can be found among the Vitex shrubs along the Gardner Center at Haverford College, across from the fieldhouse.
Cultivars of Cotinus coggygria are planted in containers around camps and range in color from ‘Golden Spirit’ to ‘Velvet Cloak.’