Quick Facts

Quick facts

• Chinese Rain Tree (Koelreuteria elegans subsp. formosana), a native of Taiwan, is an attractive deciduous tree that has been planted for ornamental purposes in the past, especially as a street tree
• It tolerates a variety of environmental conditions and has a high growth rate and high seed viability.
• It has naturalised and become invasive in Australia, particularly in south-east Queensland and the north coast of New South Wales, and has the potential to crowd out native vegetation.
• Any new infestations should be reported to the appropriate authorities so that further spread can be controlled and eradicated.

What Does It Look Like?

What is it?

Chinese Rain Tree (Koelreuteria elegans subsp. formosana) is a small to medium deciduous tree. In Australia it grows to approximately 5 m tall and up to 18 m under ideal conditions. It has a light brown, smooth trunk which can develop ridges with age. Its dense, rounded crown which can reach 10 to 15 m in diameter (CRC 2003). Its leaves are bipinnate (i.e. the leaflets are borne on a secondary axis from the main leaf axis). Each leaflet is hairless, dark green above and light green below and usually has coarsely toothed edges with a long tapering point.

Along with its attractive shape and size Chinese Rain Tree has showy branched clusters of small, yellow flowers with five petals in spring and summer.

Fruits are inflated, papery capsules up to 50 mm long in drooping clusters. They range in colour from light pink to a deep rose and contain black round seeds approximately 5 mm in diameter (CRC 2003).

Due to its attractive appearance and general hardiness it has been used as an ornamental tree in many parts of the world. It is also recorded as a weed in Japan and parts of the United States (e.g. Florida, Louisiana, Texas, Mississippi and Hawaii) (USDA 2007).

For further information and assistance with identification of Chinese Rain Tree contact the herbarium in your state.

Flower colour

Yellow

Growth form (weed type/habit)

Tree

Where it currently grows? Preferred habitat

Chinese Rain Tree is tolerant of a wide range of environmental conditions. It thrives in temperate and subtropical climates. It tolerates full sun, partial shade, drought, frost, heat, well drained to wet soils, extended flooding and air pollution. It grows on a wide range of soil types and may be tolerant of light salt spray, but not of saline conditions (CRC 2003).

Are there similar species?

Often confused with Koelreuteria paniculata which is also known as the Golden Rain Tree and has been widely planted in Australia (CRC 2003). However, K. paniculata has pinnate (leaflets off one main axis) rather than bipinnate leaves and the seed capsules are cone-shaped rather than egg-shaped (CRC 2003).

Why Is It A Weed?

What are its impacts?

Chinese Rain Tree is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia's ecosystems (CRC 2003).

Native ecosystems: The rapid growth rate and high seed viability could lead to it crowding out native plants (CRC 2003). It has the potential to be invade roadsides, disturbed sites, waste areas, parks, urban bushland, riparian vegetation, gullies, forest margins and open woodlands in the sub-tropical, tropical and warmer temperate regions of Australia (Brisbane City Council n.d.).

How does it spread?

Chinese Rain Tree reproduces by seed, which can germinate within 6-8 days. While the papery fruits suggest that it could be dispersed by wind (Staples et al. 2005) the relatively large size of the seeds (at least 5mm) suggests otherwise. The infestation of gullies in Brisbane suggests that movement by water may play a role. Birds may also disperse the seeds attracted by the colourful, plentiful fruits and seeds (CRC 2003).

What is its history in Australia?

No records could be found of when this species first arrived in Australia. Its use as a street tree in many regions suggests that it was imported for ornamental purposes. In Brisbane Chinese Rain Tree was commonly planted as an amenity/ street tree until the early 1980s when it was recognized as an environmental weed (CRC 2003).

How To Manage It?

Best practice management

Prevention: Early detection and eradication are crucial. Small infestations can be eradicated if caught early enough. It is highly recommended that any new outbreaks should be reported immediately to your state or territory weed management agency or local council. Do not try to control Chinese Rain Tree without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem (CRC 2003).

Non-chemical control: Manual control: Seedlings may be hand pulled however the large numbers of seedlings germinating can make this an onerous task (PIER 2005). 

Chemical control: Herbicide is the main control method and the species is well controlled by herbicide (PIER 2005). Control methods in Brisbane have included the application of herbicide using the cut-stump, stem injection and basal bark methods. In street areas plants are hand pulled from the pavement. Control efforts are timed to occur prior to seed formation in spring, to minimise seedbank replenishment (CRC 2003).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Chinese Rain Tree germinates in late winter. In warmer climates seed viability is high and seeds germinate quickly (within 6-8 days). While they can germinate underneath mature individuals they will only grow to maturity if sufficient sunlight can penetrate the canopy. Experimental evidence has shown that seed can remain viable for at least 10 months of moist storage at 4°C (CRC 2003).

No information is available on time to first flowering. Observations of the naturalised population at Lismore suggest that its growth rate is rapid. Flowering occurs from spring to summer with seed set occurring in late summer to early autumn. As fruits remain on the tree seed drop may occur year round (CRC 2003).

Where Is It Found?

Which states and territories is it found?

NSW, QLD

What areas within states and territories is it found?

Naturalised and well established in Brisbane and near Noosa in Queensland and near Lismore in New South Wales, where it is invading urban parks, bushland, gullies and streets (CRC 2003). It has been declared an environmental weed by the Brisbane City Council (see http://www.brisbane.qld.gov.au ) and the Ipswich Council (CRC 2003). It is also likely to be naturalised in other areas of the north coast of New South Wales (Hosking et al. 2001). There is also the potential for distribution in Western Australia and the Northern Territory (CRC 2003).

Where does it originate?

Chinese Rain Tree is a native of Taiwan where it is apparently fairly widespread (Meyer 1975).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

Not declared in any Australian state or territory.

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Koelreuteria elegans subsp. formosana

Other scientific names (synonyms)?

Koelreuteria formosana Hayata

Does it have other known common name(s)?

Chinese Flame Tree, Flamegold, Golden Rain Tree, Flame Golden Rain Tree