What is Ontario Doing?

To prevent the further spread and introduction of this unwanted invader into the province, Ontario has regulated tree-of-heaven as restricted under the Invasive Species Act, 2015.  

Background

Native to China, tree of heaven was first introduced to the United States in 1784 as an ornamental plant. Tree of heaven can tolerate a wide variety of soil conditions, which is why it was also widely used as a street tree in much of the 19th century. Tree of heaven is known as one of the most rapidly growing trees in North America, and is capable of reproducing vegetatively. It typically reproduces via wind dispersal of its dry fruits, which have a high germination rate. Tree of heaven is also capable of altering soil chemistry to make it unsuitable for other plants to grow nearby. 

Because of its highly successful reproductive traits and its ability to tolerate a variety of soil types and environmental conditions, tree of heaven is incredibly invasive.

Range

In Canada, tree of heaven can be found in British Columbia, Ontario, and Quebec. In Ontario it is mostly established in the southern areas of the province where it can take advantage of the more mild winters.

Impacts of Tree-of-Heaven

• Quickly outcompetes and crowds out native plants and alters soil chemistry to prevent other plants nearby from growing. 
• Aggressive root systems can damage pavement, sewers, and building foundations. 
• Sap can cause dermatitis and myocarditis if it enters the bloodstream. 
• Tree of heaven is the host species for the spotted lanternfly, another invasive species that was introduced to North America from China.  

How to Identify

• Can grow up to 30 m (98.4 ft) in height and 2 m (6.6 ft) in diameter. 
• When leaves are crushed a foul odor is released. 
• Leaves are large, smooth margined, and compound, alternately arranged along a central stem with 10-41 pairs leaflets. 
• Twigs are hairless and can appear green, pink, red or brown. 
• Heart-shaped leaf scars with spongy brown centers when leaves are broken off. 

What You Can Do

• Learn how to identify tree of heaven and other invasive plants, and how to effectively manage these species on your property.  
• Avoid using invasive plants in gardens and landscaping. 
• Buy native or non-invasive plants from reputable garden suppliers. See Grow Me Instead: Beautiful Non-Invasive Plants for Your Garden. 
• Dispose of invasive plants in the garbage. Do not put them in the compost or discard them in natural areas. Discarded flowers may produce seeds. 
• When hiking, prevent the spread of invasive plants by staying on trails and keeping pets on a leash. 
• If you find tree of heaven or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or visit EDDMapS to report a sighting. 

Other Resources

• Ontario Invasive Plant Council
• Ontario Ministry of Natural Resources and Forestry
• Ontario Ministry of Agriculture, Food and Rural Affairs
• Ontario Weeds
• Invasive Species Centre

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