The Mimosa tree (Albizia julibrissin) is an ornamental species valued for its rapid growth and showy pink flowers. Introduced to the United States from Asia in the 1700s, it quickly became a popular landscape choice. Despite its beauty, the Mimosa tree is classified as an invasive species in many regions due to its aggressive spread and problematic root system. Managing this tenacious root structure and its ability to regenerate is the central challenge for property owners.
The Structure and Behavior of Mimosa Roots
The Mimosa tree possesses a root system adapted for aggressive colonization. Its roots are generally shallow, with a few large-diameter roots near the trunk. This structure makes the tree susceptible to wind damage but allows it to quickly access surface nutrients and water. This shallow habit contributes to surface root development that can spread far beyond the tree’s canopy.
A defining characteristic of the Mimosa root system is its capacity for nitrogen fixation, a process typical of legumes that enriches the surrounding soil. This biological advantage allows the tree to thrive in nutrient-poor or disturbed soils, giving it a competitive edge over native plants. The roots readily engage in vegetative reproduction through root suckering.
Root suckering occurs when lateral roots produce genetically identical clones that sprout up as new trees, often several feet from the parent trunk. Damage or disturbance to the shallow root system, such as cutting the main trunk or tilling the soil, stimulates the production of these suckers. This vegetative propagation makes simple mechanical removal highly ineffective, as root fragments left behind quickly resprout into multiple new stems.
Environmental and Infrastructure Consequences
The aggressive behavior of the Mimosa root system leads to environmental and structural problems. Its shallow, spreading roots easily cause physical damage to hardscaping and infrastructure. As the roots grow in diameter, they exert pressure that can lift and crack concrete sidewalks, driveways, and patios.
The rapid growth enabled by nitrogen fixation allows Mimosa to out-compete surrounding vegetation. It quickly forms dense stands, especially in disturbed areas like roadsides, shading out native flora and reducing biodiversity. The root system’s ability to seek out moisture means that in dry conditions, roots may be drawn toward water sources like sewer or drainage pipes, potentially leading to blockages and costly damage. Once established, the tree’s fast growth, prolific seed production, and vegetative spread ensure that removal is a complex, multi-year undertaking.
Comprehensive Management and Eradication Strategies
Effective eradication of the Mimosa tree requires a persistent, multi-faceted approach targeting both the trunk and the root system. Mechanical removal alone is rarely successful because cutting the trunk often triggers aggressive root suckering from the remaining roots. For smaller seedlings, hand-pulling is feasible, but the entire root structure must be removed since even small fragments can resprout.
For established trees, the most reliable method is the cut-stump method, which combines cutting with chemical treatment to prevent regrowth. The tree is cut horizontally near ground level. A concentrated, systemic herbicide, such as glyphosate or triclopyr, must be applied immediately to the freshly cut surface. The application should focus on the cambium layer, the narrow ring just inside the bark, where the herbicide is efficiently transported down to kill the entire root system.
Another chemical control option is the basal bark application, suitable for smaller trees with smooth bark. This method involves spraying a mixture of herbicide, usually triclopyr ester mixed with a penetrating oil, around the entire circumference of the lower trunk. The mixture is applied from the ground line up to 15 inches, allowing the herbicide to be absorbed through the bark and translocated to the roots. This technique is effective year-round, provided the ground is not frozen.
Long-term management is necessary to control the emergence of new root suckers and seedlings. New suckers should be addressed as soon as they appear, preferably by cutting them low and immediately spot-treating the cut point with a brush-on herbicide. Repeated mowing or regular cutting of new growth over several growing seasons can exhaust the root system’s stored energy reserves. Consistency in follow-up treatments is the most important factor in achieving complete eradication.