Quick Facts

Quick facts

• Originally from China, Tree-of-heaven (Ailanthus altissima), is a deciduous suckering tree to 10-20 metres tall with large pinnate (divided) leaves with up to 20 leaflets per leaf.
• Invades areas by producing large numbers of wind dispersed seeds, suckering and root segments.
• It establishes dense mono-cultures which exclude other species.
• Leaves, bark and flowers produce substances which are toxic to livestock, humans,  and are known to inhibit the growth of other plants.
• Control of the species is difficult requiring careful removal of potential propagules (such as seeds, roots and stumps), poisoning and repeated treatments are required.
• Trees that are cut down, burnt or bulldozed encourage profuse suckering and spread.

What Does It Look Like?

What is it?

Tree-of-heaven (Ailanthus altissima) is a fast growing, deciduous tree usually up to 10 m high but may reach 20 m, often suckering and forming thickets. The bark is smooth and grey. and branches (branchlets) are relatively soft and have an obvious pith. Leaves are alternately arranged along the stem, appear (borne) in spring, are dark green, and in autumn turn yellow and fall. Leaves are large 200-800 mm long, and divided into leaflets some times up to 20 leaflet pairs per leaf, oblong in outline. The petiole (leafing stalk) is 40-130 mm long. Pinnate leaves are either imparipinnate (with an odd number of leaflets terminated by a single leaflet), or paripinnate (having an even number of leaflets terminated by a pair of leaflets). Each leaflet is ovate (egg-shaped) to broadly lance-shaped and can be 40-140 mm long and 20-50 mm wide. The margins are toothed or lobed near the base and each tooth or lobe is tipped with a gland. The bark, crushed leaves and flowers have a bitter smell.

The plants are dioecious (individual plants have all male flowers or all female flowers) or they can have mostly male flowers with some bisexual flowers, or mostly female flowers with some bisexual flowers. The flowers are white, arranged at the end of branches in large panicles (branched clusters) 60-120 mm long. Flowers are small, petals about 2-3 mm long and woolly towards the base. Stamens (male reproductive structures) slightly exceeding petals, are dimorphic, (two different kinds of stamen), up to about 2.5 mm long in male flowers. The five fused carpels (the female reproductive structures) are about half petal length of petals.

The fruit is oblong-elliptic, 40-05 mm long, and 6–10 mm wide, yellowish turning reddish, papery and surrounds the solitary seed. Its slightly twisted shape produces a twirling action when it falls from the tree ( Harden 2007; VicFlora 2016).

Recognition: This species can normally be recognised by the combination of the following characters;  fast growing, deciduous tree usually up to 10-20 metre tall; suckering plant; large leaves 200-800 mm long, divided into leaflets some times up to 20 leaflet pairs per leaf; leaflet margins are toothed or lobed near the base and is tipped with a gland; Flower and fruit borne at tip of erect branches.

For further information and assistance with identification of Tree-of-heaven, contact the herbarium in your state or territory.

Flower colour

White

Growth form (weed type/habit)

Tree

Where it currently grows? Preferred habitat

Tree-of-heaven occurs in a range of habitats, escaping from rural, garden and street tree plantings. It spreads readily in disturbed sites (farmland, railway lines, roadside etc.) and along watercourses. It grows well in poor soils and full sunlight (GISD 2005). It is tolerant of shade and has been reported growing on the banks of the Colo River in New South Wales, under dense native vegetation (Rodd 2002). It is known to grow in very thin soils and tolerate a wide range of pH levels. It can tolerate drought and saline soils (Hoshovsky 1988).  It will establish in urban areas, sending suckers some distance under paths or even small roads.

Are there similar species?

Red Cedar (Toona ciliata) and Pencil Cedar (Polyscias murrayi) may be confused with Tree-of-heaven. Both are trees which occur in the rainforests of eastern Australia. Neither of these trees have a gland on the base of the leaflets, or an unpleasant smell when the leaves are crushed.

The noxious weeds Rhus (Toxicodendron succedaneum), Honey Locust (Gleditsia triacanthos) and Black Locust (Robinia pseudoacacia) are similar smaller trees. They have compound leaves which do not have a gland on each leaflet. The fruit of Rhus is globular, whereas for Black and Honey Locust the fruits are pods. Rhus is confined to New South Wales, whereas Honey and Black Locust are found in the Australian Capital Territory, New South Wales, Victoria, South Australia and Western Australia (AVH 2007).

Why Is It A Weed?

What are its impacts?

Tree-of-heaven (Ailanthus altissima) exhibits typical characteristics of an invasive weed. It has efficient dispersal and reproductive qualities and the ability to form dense monocultures (Call & Nilsen 2005). Tree-of-heaven is a deciduous tree with a tendency to sucker extensively from its roots, forming dense thickets and outcompeting other desirable plants (DPI NSW 2019). This species primarily occurs in disturbed areas, but its winged seeds can blow considerable distances and it may also invade undisturbed habitats (DEEDI 2020).

It is mildly toxic to humans with mild symptoms of headache and nausea if ingested in large quantities. The sap is a skin and eye irritant causing rashes, dermatitis and conjunctivitis, and the pollen can cause allergic reactions such as hay fever (DPI NSW 2019). The toxicity levels are highest in the leaves during the early part of the growing season (Mergen 1959; GISD 2005). It inhibits post-disturbance succession by other plants by creating a relatively toxic soil environment (Lawrence et al. 1991).

Agriculture: Not a known weed of agriculture as cultivation and cropping do not allow for its establishment. However, it can sucker from planted stands in homesteads and other areas growing under fence lines. The species has toxins in its bark, leaves and flowers which inhibit the growth of other plants, and are toxic to animals.

Native ecosystems:  Tree of heaven (Ailanthus altissima) is regarded as an environmental weed in New South Wales, the ACT, Victoria, South Australia, Queensland and Western Australia . It spreads into bushland from old homestead sites and other plantings, and is particularly invasive in riparian vegetation and along gullies and can also invade dry sclerophyll forests and other woodlands (DEEDI 2020). Tree-of-heaven out-compete native species for nutrients and light, often completely displacing these species and forming monospecific (single) stands. Is an aggressive competitor due to its allelopathic properties (inhibits germination of other seeds), ability to tolerate a wide range of soils, and the abundant suckers it produces from shallow roots. Will shade out smaller plants and spreads rapidly via highly viable wind dispersed seed (Brown & Bettink 2009). For example, in Wellington, New South Wales, it is likely to overtake the rocky outcrop on which the rare species Zieria obcordata occurs and out-compete numerous other native species (Bannerman 2005).

Urban areas:  Can sucker in garden and roadside spreading to neighbouring land even under roads.  It can withstand harsh urban environments better than most plants (Parsons and Cuthbertson 1992). The roots of Tree-of-heaven can also damage piping and foundations (GISD 2005).

How does it spread?

Tree-of-heaven disperses by seed and vegetative suckering. Dumped root segments can also take root and segments spread by machinery during clearing activities can easily re-sprout. Stumps re-sprout after cutting and have been reported to grow at a rate of 3 cm per day in the United States (GISD 2005).

A single mature tree can produce about 300,000 seeds each year. The seeds are winged and can be carried a fair distance from the parent plant by the wind or by water. One plant reproducing from suckers can become a large clump very quickly (Hoshovsky 1988). It has been reported as being able to sucker from roots for at least 4 years after a tree is cut down, sometimes many metres from the parent plant (Blood 2001).

What is its history in Australia?

Tree-of-heaven was originally brought to Australia as a garden plant and shade tree and was used in urban and rural locations. It was recorded at Camden Park, New South Wales in 1845 and in the Melbourne, Hobart and Adelaide Botanic Gardens in the 1850s. It was also introduced in the 1860s by Chinese miners (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

If possible, Tree-of-heaven (Ailanthus altissima) is best controlled in the early stages of establishment by seed. If not removed, larger plants  will sucker from the roots when the main plant is cut down or poisoned, and may continue to do so for some years. For this reason, repeat treatment with herbicide will be necessary.

Chemical control: Various herbicide are effective and available for application via various methods. Plants too big for manual removal, but still small plants  should be foliar sprayed. For small-medium sized young plants the basal bark method can be used, and for older large plants the cut-and-swab method (Cut stump treatment, cut and painted) or the stem injected method can be used.

Foliar spraying: Spay all leaves of young small plants with systemic herbicide. Basal barking: Starting at the base of each stem, paint all the way around the stem to a minimum height of 30 centimetres ensuring the treated area is not disturbed for at least 24 hours to allow herbicide uptake. This method can take weeks to months. Stem injection (drill-and-fill): Using a drill or similar tool cut downward at an angle of 45 degrees through the bark to the sap wood.  Immediately apply the herbicide mixture penetrating the trunk to a depth which reaches the sapwood and they must be angled downwards to enable the herbicide to pool. Take care not to overfill the holes. and ensure the treated area is not disturbed for 24 hours to allow herbicide uptake. Treat each stem of the plant with cuts every 7.5 centimetres around the trunk's entire circumference. Create two rows of pockets around the tree (one slightly higher, the next row lower and offset from the first). Cut-and-swab method (Cut stump treatment or cut and painted): Cut the stem  no more than 15 centimetres from the ground and immediately apply the herbicide mixture to the cut surface of the stump. If you do not apply the herbicide immediately the plant will seal itself off and the herbicide will not enter the plant. 

For a summary of treatment and applications see; DPI NSW 2019.  Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au. NOTE: Training is normally a requirement in most States and Territories for all or some of the methods.

Non-chemical control: Non chemical control methods are usually followed up with chemical (herbicide) applications. Do not cut trees down without applying herbicide to the stump or massive suckering will result. Physical control: Manual removal of young seedlings is the best way to remove the future problem. Small seedlings and the roots can be pulled out of the ground after rain when the soil is loose. This facilitates removal of the entire rooting system, which may otherwise re-sprout if left in the ground. If left until the taproot develops, total removal of the roots system will be difficult (Hoshovsky 1988). 

Ploughing, or slashing of small plants, will also result in massive suckering so is not advised. Burning is not recommended as the trees will re-sprout vigorously after fire (Burch & Zedaker 2003).

Biological control: There are currently no biological controls for Tree-of-heaven.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Seeds germinate in spring and the young plants develop extensive root systems in the first year. Seedlings establish a taproot about 3 months after germination. The leaves turn yellow and fall in autumn and new green leaves appear in mid spring. Plants flower from 2 years old. Tree-of-heaven flowers in most states from November to January but has been reported to flower as late as autumn in western New South Wales. Fruit ripens about 3 months later and may remain on the tree over the following winter. Individual plants live for at least 50 years (Cunningham et al. 1992; Walsh & Entwisle 1999; Parsons & Cuthbertson 2001; GISD 2005).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, SA, VIC, WA

What areas within states and territories is it found?

Tree-of-heaven is found in disturbed areas, particularly those associated with old homesteads, roadside plantings, gardens and other urban areas where it has escaped from cultivation. It is naturalised in coastal New South Wales as well as the north-west, central-west and south-west areas of that state and the Australian Capital Territory (Harden 2007). In Victoria there are scattered occurrences across the state with a large infestation around the town of Mildura in the far north-west (Victorian Resources Online 2007). In South Australia it is mainly recorded in the Mount Lofty Ranges, with a few outliers in the far south-east corner, riverland and just south of dry (semi-arid) Port Augusta (AVH 2020). In Western Australia it occurs near Perth and in the southern wheatbelt (Hussey et al. 1997, Western Australian Herbarium 1998-). It is also recorded in the southeast region of Queensland (Batianoff & Butler 2002).

Where does it originate?

Tree-of-heaven is native to Taiwan and central China occurring from 22^o to 34^o north in latitude (Howard 2004).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT, VIC

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

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

Ailanthus altissima

Other scientific names (synonyms)?

• Ailanthus altissimus (Miller) Swingle
• Ailanthus glandulosa Desf.
• Ailanthus rhodoptera F.Muell.
• Ailantus rhodoptera F.Muell. (incorrect spelling)
• Toxicodendron altissimum Mill.

Does it have other known common name(s)?

Chinese Sumac, Stinking Cedar, Copal Tree, Varnish Tree, Hemelboom, Stinking Cedar.