Introduction
This slow growing, open-crown, round, small tree eventually reaches to 12 to 15 feet tall (occasionally 20) and 10 to 12 feet wide. The large panicles of wispy purple-colored flowers produced in spring and early summer give the effect of a cloud of smoke. They make a wonderful accent in a shrub border and can be planted as a specimen or as a patio tree where the black, showy, multiple trunk can be displayed. Planting smoketree is a good way to extend the spring flowering-tree season into the summer before the Crape-Myrtles come into full bloom. This cultivar has deep purple leaves which keep their color all summer long. Fall color is usually a rich red-purple. Many people grow it simply to enjoy the spectacular fall color.
Credit: Ed Gilman
General Information
Scientific name: Cotinus coggygria
Pronunciation: koe-TYE-nus koe-GUY-gree-uh
Common name(s): 'Royal Purple' Smoketree, `Royal Purple' Wig-Tree, `Royal Purple' Smokebush
Family: Anacardiaceae
USDA hardiness zones: 5B through 8B (Fig. 2)
Origin: not native to North America
Invasive potential: little invasive potential
Uses: specimen; deck or patio; street without sidewalk; container or planter; reclamation; trained as a standard; screen; parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; tree lawn 3-4 feet wide; tree lawn > 6 ft wide; tree lawn 4-6 feet wide; highway median
Availability: not native to North America
Description
Height: 12 to 15 feet
Spread: 10 to 18 feet
Crown uniformity: symmetrical
Crown shape: round
Crown density: dense
Growth rate: slow
Texture: medium
Foliage
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: entire
Leaf shape: obovate, elliptic (oval)
Leaf venation: reticulate, pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: purple/red
Fall color: red, purple
Fall characteristic: showy
Flower
Flower color: red, purple
Flower characteristics: very showy
Fruit
Fruit shape: oval, irregular
Fruit length: less than .5 inch
Fruit covering: dry or hard
Fruit color: brown
Fruit characteristics: does not attract wildlife; showy; fruit/leaves not a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; showy; typically multi-trunked; thorns
Pruning requirement: little required
Breakage: resistant
Current year twig color: brown
Current year twig thickness: medium, thick
Wood specific gravity: unknown
Culture
Light requirement: full sun
Soil tolerances: clay; sand; loam; acidic; alkaline; well-drained
Drought tolerance: high
Aerosol salt tolerance: moderate
Other
Roots: not a problem
Winter interest: no
Outstanding tree: yes
Ozone sensitivity: unknown
Verticillium wilt susceptibility: susceptible
Pest resistance: resistant to pests/diseases
Use and Management
The tree is tough and adapts to restricted soil spaces. It could be used along a street under power lines and would not require pruning for many years. It is a small tree, well-adapted to urban areas with almost year-round interest which should be used more in our landscapes.
Smoketree grows best in a sunny location and a well-drained loam. It will grow asymmetrically and lean toward the light in a partially sunny area, so it is best to locate it in full day sun where the crown will develop symmetrically. Though sometimes short-lived in rich soil, Smoketree is useful in dry, rocky soil where there is no irrigation. It also grows in a wide range of soil pH, including alkaline. Probably short-lived (20 years - maybe more) in most situations but who cares - the tree is great while it's around!
Propagation of cultivars is by cuttings.
Cultivars include: `Daydream' - heavy production of panicles, dense habit of growth; `Flame' - brilliant orange-red fall color, pink inflorescences; `Nordine' - resembles `Royal Purple'; `Notcutt's Variety' - dark maroon-purple leaves (also known as `Foliis Purpureis Notcutt's Variety' and `Rubrifolius'); `Purpureus' - leaves bronze-green, inflorescences purplish-pink; `Pendulus' - pendulous branches; and `Velvet Cloak' - dark purple-leaf form, spectacular fall color of reddish-purple.
Pests
Oblique-banded leaf roller mines and rolls the leaves, usually in June. The insect rarely occurs in sufficient numbers to warrant control. When it does occur they can be picked off by hand or sprayed with Bacillus thuringiensis .
Diseases
Leaf spots can be caused by various genera of fungi but are usually not serious.
Scab may cause leaf drop. No controls are listed.
The most serious disease is Verticillium wilt. Smoketree is very susceptible, and entire branches wilt and die. Prune out infected branches, fertilize, and water the plant during dry weather.
A stem canker can be a problem in the eastern U.S.