Koelreuteria bipinnata: Chinese Flame-Tree1
A yellow carpet of fallen petals, delicate leaflets which cast a mosaic of welcoming shade, and large clusters of persistent rose-colored, papery capsules all help to make Chinese flame-tree a very popular landscape tree over a wide area of the South. One of only a few yellow-flowering trees for the mid- and deep-south landscape. This broad-spreading, deciduous tree reaches a height of 40 to 60 feet and eventually takes on a flat-topped, somewhat irregular silhouette. It is often used as a patio, shade, street, or specimen tree. The small, fragrant, yellow flowers appear in very showy, dense, terminal panicles in early summer, and are followed in late summer or fall by large clusters of the two-inch-long "Chinese lanterns". These papery husks are held above the foliage and retain their pink color after drying and are very popular for use in everlasting flower arrangements. The bark on Chinese flame-tree is smooth and light brown when young, becoming ridged and furrowed as the tree matures. It is easily distinquished from Koelreuteria paniculata since Koelreuteria bipinnata has more upright branches and has twice compound leaves, whereas Koelreuteria paniculata has single pinnate compound leaves.
Scientific name: Koelreuteria bipinnata
Pronunciation: kole-roo-TEER-ee-uh bye-pih-NAY-tuh
Common name(s): Chinese flame-tree, bougainvillea goldenrain tree
USDA hardiness zones: 7A through 10A (Fig. 2)
Origin: not native to North America
Invasive potential: This one is not listed on the UF/IFAS Assessment of the Status of Non-Native Plants in Florida's Natural Areas
Uses: reclamation; shade; street without sidewalk; specimen; 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; container or planter
Availability: not native to North America
Height: 20 to 35 feet
Spread: 25 to 35 feet
Crown uniformity: irregular
Crown shape: round
Crown density: open
Growth rate: fast
Leaf arrangement: alternate (Fig. 3)
Leaf type: bipinnately compound
Leaf margin: incised, serrate
Leaf shape: ovate, oblong
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: green
Fall color: yellow
Fall characteristic: showy
Flower color: yellow
Flower characteristics: very showy
Fruit shape: oval, elongated
Fruit length: 1 to 3 inches
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; not showy; typically one trunk; thorns
Pruning requirement: needed for strong structure
Breakage: susceptible to breakage
Current year twig color: brown
Current year twig thickness: very thick
Wood specific gravity: unknown
Light requirement: full sun
Soil tolerances: clay; sand; loam; alkaline; acidic; extended flooding; well-drained
Drought tolerance: high
Aerosol salt tolerance: moderate
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
Trees need to be trained when young to develop a strong branch structure. On weak-wooded trees such as Chinese flame-tree, spacing main branches apart along a central trunk is crucial to developing a durable tree. As soon as you see them, remove any double or multiple trunks which develop, especially if they have embedded or pinched bark in the branch crotch. Be sure to locate the first major branch high enough off the ground so that drooping leaves and branches will not get in the way of traffic below. Train major branches so they grow up and out, spreading from the trunk to create the clearance needed for street tree or parking lot planting.
The tree definitely has a place in many landscapes. Planted in a full sun location, Chinese flame-tree makes a moderately dense shade tree, but there is considerable variation among individuals of the species. Properly pruned and trained trees can be planted as street or parking lot trees, but do not commit large areas to Chinese flame-tree due to the possibility of them breaking up as they reach about 30 years old. They will be the source of many compliments when they are in flower and fruit.
This is a tough tree which should be grown in full sun on any well-drained soil, in sand or heavy clay, and should receive moderate watering. The tree becomes leggy and thin in partial shade. When well-established, it tolerates wind, air pollution, salt, heat, and drought.
Propagation is by seed, which will germinate within six to eight days.
Some nurseries are mistakenly growing Koelreuteria elegans or Koelreuteria formosana which are only cold hardy to USDA hardiness zone 9 instead of Koelreuteria bipinnata which is cold hardy to USDA hardiness zone 7b. This problem has given Chinese flame-tree a bad name in some areas of the mid-south. Be sure to get northern seed source for propagation to ensure cold hardiness in the northern part of its range.
Pests and Diseases
No pests or diseases are of major concern. Root rot on old trees. A canker causes dead and sunken areas on the bark. Coral pink fruiting bodies develop on the diseased bark. Prune out infected branches and fertilize to maintain tree health.
Verticillium wilt attacks Koelreuteria. The disease causes wilting and death of leaves on infected branches. Eventually the entire tree may be killed. Fertilize to stimulate growth. There are no chemical controls.