The tree-of-heaven, or Ailanthus altissima, has gained notoriety not only for its invasive properties and its role as a host for the destructive spotted lanternfly but also for its various health risks to humans. While it's not considered acutely deadly like some highly toxic plants, it contains a variety of phytochemicals that can cause adverse reactions, particularly through skin contact and inhalation.
Contact Dermatitis and Skin Irritation
Direct contact with the sap from the tree-of-heaven can trigger allergic contact dermatitis, an itchy rash similar to poison ivy. The sap is found in all parts of the plant, including the leaves, branches, bark, and seeds. Symptoms of this skin irritation can include redness, swelling, and a rash, with severity depending on the individual's sensitivity and the extent of contact. Gardeners, landscapers, or anyone engaged in removing this invasive species should exercise caution and wear protective clothing to prevent exposure.
The Allergic Response
The allergic reaction is caused by compounds within the sap, such as the quinone 2,6-dimethoxybenzoquinone. Exposure is a particular risk for those with cuts, blisters, or broken skin, which can allow the compounds to enter the bloodstream.
Allergic Reactions to Pollen and Odor
Beyond skin contact, tree-of-heaven can also cause respiratory and allergic issues. Male trees produce large amounts of pollen, which can be a significant allergen for some individuals, leading to hay fever, rhinitis, and conjunctivitis. Additionally, the crushed leaves and flowers of the tree emit a strong, offensive odor, often compared to rancid peanut butter or cat urine. For some, this intense smell can cause headaches and nausea.
Rare but Serious Cardiac Complications
In very rare instances, extensive exposure to tree-of-heaven sap, especially through broken skin, has been linked to more serious health problems, including myocarditis. Myocarditis is an inflammation of the heart muscle, and documented cases have included symptoms such as:
- Fever and chills
- Chest pain
- Shortness of breath
- Heart palpitations
These severe reactions underscore the importance of minimizing contact and taking protective measures, particularly for those performing extensive removal work.
Oral Ingestion: Not Recommended
While there is some historical use of tree-of-heaven in traditional medicine, largely derived from the bark, modern sources strongly advise against ingesting it. There is insufficient reliable scientific evidence to support any purported health benefits, and risks are associated with consuming the plant. Potential side effects from oral ingestion can include nausea, dizziness, headaches, and diarrhea. Furthermore, research has shown that the plant contains toxins like ailanthone, which can be toxic to the liver and gastrointestinal tract in higher doses.
Identification and Look-alikes
Correct identification is crucial to avoid unintended contact. Tree-of-heaven is often confused with native trees like Staghorn Sumac and Black Walnut, both of which have pinnately compound leaves. A comparison can help distinguish them.
Tree-of-Heaven vs. Common Look-alikes
| Feature | Tree-of-Heaven (Ailanthus altissima) | Staghorn Sumac (Rhus typhina) | Black Walnut (Juglans nigra) |
|---|---|---|---|
| Leaflet Edge | Mostly smooth, with one or two glandular teeth at the base. | Serrated (toothed) edges along the entire length. | Serrated (toothed) edges. |
| Odor (crushed leaves) | Offensive, resembling rancid peanut butter. | No strong, offensive odor; some may detect a mild scent. | No unpleasant odor; leaves are fragrant. |
| Bark | Smooth and gray on young trees, developing a cantaloupe-like texture with age. | Fuzzy on younger stems, smooth on older bark. | Deeply furrowed, dark gray or black. |
| Fruit | Twisted, winged samaras (seeds) in clusters. | Upright clusters of fuzzy red berries. | Large, round green husks containing a nut. |
Conclusion
While the tree-of-heaven may not be the most deadly plant in nature, its various health risks—from common skin rashes and allergies to rare but severe heart inflammation—make it a species to handle with extreme caution. When planning to remove or work near this invasive tree, always wear appropriate protective gear, including gloves, long sleeves, and safety glasses. Educating yourself on its identifying characteristics is also essential to avoid accidental exposure. In case of accidental contact or adverse reaction, consult a healthcare professional, especially if symptoms are severe or concerning. For more detailed information on controlling this invasive plant, consult reputable sources like the Penn State Extension.
