Introduction

American Smoketree is most often seen as a large shrub 15 to 20 feet tall when grown in cultivation but can slowly become a 20 to 30-foot-tall, rounded tree with time, or in the wild. The bark on older specimens flakes off at the base of the trunk showing a dark grey to black exfoliating character. Multiple trunks eventually become twisted and gnarled. The 7 to 12-inch, fairly sparse, fuzzy panicles of springtime flowers give the plant an unusual, somewhat smoky effect but American Smoketree is most outstanding for its beautiful foliage. The five to six-inch-long leaves are pinkish-bronze when young, mature to a lush, dark blue/green then, in autumn, change into gorgeous shades of yellow, red, orange, or purple. Very striking in the fall, one of the best for fall color since it lasts three to four weeks. Enough cannot be said about the fall color - it must be seen to be believed. Not seen often enough in cultivation, American Smoketree may be in danger of extinction in the wild due to the large trees having been harvested for the yellow and orange dye found in their wood.

General Information

Scientific name: Cotinus obovatus

Pronunciation: koe-TYE-nus ob-oh-VAY-tus

Common name(s): American Smoketree, Chittamwood

Family: Anacardiaceae

USDA hardiness zones: 5A through 8B (Fig. 2)

Origin: native to North America

Invasive potential: little invasive potential

Uses: deck or patio; specimen; street without sidewalk; container or planter; reclamation; trained as a standard; parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; sidewalk cutout (tree pit); tree lawn 3-4 feet wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; urban tolerant; highway median

Availability: somewhat available, may have to go out of the region to find the tree

Description

Height: 20 to 30 feet

Spread: 15 to 25 feet

Crown uniformity: symmetrical

Crown shape: round

Crown density: moderate

Growth rate: slow

Texture: medium

Foliage

Leaf arrangement: alternate (Fig. 3)

Leaf type: simple

Leaf margin: entire

Leaf shape: elliptic (oval), obovate

Leaf venation: pinnate

Leaf type and persistence: deciduous

Leaf blade length: 2 to 4 inches, 4 to 8 inches

Leaf color: blue or blue-green, green

Fall color: yellow, red, orange, purple

Fall characteristic: showy

Flower

Flower color: pink, white/cream/gray

Flower characteristics: showy

Fruit

Fruit shape: oval

Fruit length: less than .5 inch

Fruit covering: dry or hard

Fruit color: pink

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: needed for strong structure

Breakage: resistant

Current year twig color: gray, brown

Current year twig thickness: medium

Wood specific gravity: unknown

Culture

Light requirement: full sun, partial sun or partial shade

Soil tolerances: clay; sand; loam; alkaline; acidic; well-drained

Drought tolerance: high

Aerosol salt tolerance: low

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

Smoketree is best used in a shrub border, or trained as a multiple-trunked patio or accent tree. It can be pruned to provide clearance beneath to allow for pedestrians to pass or for use as a street tree. The tree should be used more often in American landscapes.

A North American native, American Smoketree is tolerant of a wide range of adverse urban conditions - wet soil, wind, drought, and compacted soil. Plants grow well and are native to high pH, alkaline soil and should be located in full sun or partial shade. Best flowering, form, and overall attractiveness is achieved in full sun. May need occasional irrigation on sandy soil. It is reportedly difficult to transplant but this is easily overcome by growing in containers.

The cultivar `Red Leaf' is popular for its especially brilliant fall color. Other cultivars selected for consistent and superior fall color are likely to be made available in the near future.

Propagation is by seed (with difficulty), cuttings, or layering.

Pests and Diseases

No pests or diseases are of major concern.