The name “mimosa tree” commonly refers to the ornamental Silk Tree, Albizia julibrissin. This plant is considered toxic, particularly when parts of it are ingested, due to specific chemical compounds. While the risk of severe poisoning for an adult is low, the tree contains substances that can cause unpleasant and potentially harmful reactions, especially in children and pets. Homeowners should understand which parts of the plant pose a risk and the nature of the toxins involved.
Clarifying the Species
The term “mimosa tree” causes confusion because it is used for two distinct genera in the pea family (Fabaceae). The tree commonly recognized as the mimosa, with delicate, pink flowers, is the Silk Tree, Albizia julibrissin. This species is the focus of toxicity concerns due to its widespread use as a landscape tree.
The true Mimosa genus includes plants like the sensitive plant (Mimosa pudica), which are small shrubs. Although Mimosa pudica contains the toxic compound mimosine, the toxicity discussion focuses predominantly on Albizia julibrissin. Albizia julibrissin is the large ornamental tree that produces numerous long, flat seed pods.
Toxicity Profile and Symptoms
The toxicity of Albizia julibrissin is concentrated in the seeds, seed pods, and bark. These parts contain chemical defenses, primarily alkaloids and triterpenoid saponins, that act as toxins when consumed. The seed pods contain alkaloids that are structurally similar to vitamin B6 (pyridoxine) and interfere with the vitamin’s normal function in the body.
Pyridoxine is necessary for producing neurotransmitters, and its antagonism can lead to neurological symptoms. In severe cases, this can manifest as muscle tremors, exaggerated responses to stimuli, and convulsions. The large, hard seed pods contain the highest concentration of these neurotoxic alkaloids, making them the most dangerous part of the plant if swallowed.
The bark and other parts of the plant contain triterpenoid saponins, such as julibrosides, which are irritating compounds. Ingestion of these substances typically results in localized irritation and gastrointestinal distress. Symptoms include a burning sensation in the mouth and throat, nausea, vomiting, and diarrhea. While small ingestion is unlikely to cause severe neurological issues, significant digestive upset is possible.
Handling and Exposure Management
Accidental ingestion of Albizia julibrissin requires immediate attention, especially for children due to their smaller body mass. If any part of the plant, particularly seeds or pods, has been consumed, first remove any remaining plant matter from the person’s mouth. If the person is conscious, offer a small amount of water to rinse the mouth and dilute irritants.
The most important step is to immediately contact a regional Poison Control Center for expert guidance, as they assess the risk based on the amount ingested and the person’s symptoms. The national Poison Help Line is 1-800-222-1222, and this number should be called even if the person appears well. For severe symptoms like difficulty breathing, altered mental status, or seizures, contact emergency services immediately.
Contact with the plant can sometimes cause a mild skin reaction, though this is not a primary concern with this species. If skin irritation or a rash develops after touching the leaves or bark, thoroughly wash the affected area with soap and water. For persistent irritation, a cold compress or a mild topical steroid cream may help, but consult a healthcare professional if the reaction is severe.