Tree-of-heaven

Identification & Biology
Alias' : stinking sumac, Chinese sumac, varnish tree, stink tree, paradise tree
Latin Name : Ailanthus  altissima
Category : Terrestrial Plants
Description :
  • Grows to 24 meters in height  and 1.8 m in diameter 
  • Pale gray bark, light brown twigs  
  • Large pinnately compound leaves  
  • Resembles sumacs and hickories, but is easily recognized by the glandular, notched base on each leaflet and by the offensive odour it emits  
  • Blooms in late spring creating small flowers ranging in color from green to orange   
  • Fruit is flat, papery, and twisted  

 

Tree-of-heaven first arrived to North America in the late 1800s, brought to California by Chinese miners during the gold rush. Its common name refers to its rather tall height. It is a competitive, fast growing tree that reproduces primarily by seed. It produces up to 300,000 seed per tree in a year, which can be spread by wind, water, birds, and farm equipment. Seeds remain viable in the soil for no more than a year or two. Tree-of-heaven can also regrow from the stump or lateral roots if cut or disturbed.  

Tree-of-heaven is often confused with native sumacs, such as the smooth sumac (Rhus glabra). Tree-of-heaven can be distinguished from smooth sumac by its pungent odour when its leaves and stems are crushed. Some describe the smell as burnt rubber. The other  noticeable  difference between these species is in the leaves; smooth sumac leaves are serrated and/or toothed while tree-of-heaven leaves are smooth.  

Look Alikes
Habitat

Native to central China, it can tolerate poor soils and can grow in disturbed urban areas where it sprouts up in alleys, sidewalks, parking lots and streets. In rural areas, tree-of-heaven can grow in fields, along roadsides, lakeshores, and forest edges. Tree-of-heaven is intolerant of flooding and deep shade. It is now widespread throughout British Columbia.  

Impact & Risks
  • Prolific seed producer and can successfully compete with native vegetation.  
  • Can develop dense thickets of cloned trees. 
  • Chemicals in leaves, bark, roots and seed that suppress the growth and germination of surrounding plants (i.e. allelopathic effect). 
  • The aggressive root system can cause damage to sewers and foundations.  

 

Prevention & Mitigation
  • Do not trade or grow tree-of-heaven.   
  • Regularly patrol your property for  invasive trees  and immediately control or remove  new seedlings.  
  • Cooperate with adjacent landowners and encourage them to prevent  invasive tree  spread.  
  • Immediately re-vegetate disturbed, bare soils with a suitable seed mixture that provides dense, early colonization to prevent  invasion.  
  • Do not move contaminated soils to a new area.  
Treatment & Disposal
  • Seedlings can be hand-pulled or dug out when the soil is moist.  
  • For saplings or young trees, root grubbing or mechanical extraction of roots may be effective.  
  • Bulldozing, mowing and brush-cutting can also be effective, but only if all re-sprouts are continually cut and removed throughout the growing season. A cutting method is more effective as a treatment if followed up with chemical treatment.  
  • Girdling may also be an inexpensive and useful technique for control, which involves  manually cutting away bark and  cambial  tissues around the trunks of trees. This control method should be undertaken using an ordinary axe in the spring when the trees are actively growing.   
  • Before applying herbicides, read the label for full use and precautionary instructions.  
  • For further information on the selection and application of chemicals to protect your crop, contact AgriService BC at 1-888-221-7141 or email AgriServiceBC@gov.bc.ca. 
  • There are currently no biocontrol agents (natural insect enemies) for tree-of-heaven.   
Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.