The visible portion of a tree extending from the soil is often called the trunk. However, where this trunk meets the ground, there is a specific area that plays an important role in the tree’s health and stability. This base is not merely the end of the trunk but a distinct anatomical region. Understanding this part of a tree reveals how it remains anchored and thrives in its environment.
The Root Flare and Buttress Roots
The visible base of a tree, where the trunk naturally widens and transitions into the root system, is known as the root flare (also called the root collar or trunk flare). This widening just above and slightly below the soil line, indicating a healthy connection to its main roots. An exposed root flare should be visible, as it signifies correct planting depth and allows for air exchange. If the tree appears like a “telephone pole” directly entering the ground without this flare, it suggests it may be planted too deeply.
For larger or older trees, especially those in tropical environments with shallow soils, prominent, plate-like roots extending outwards from the trunk are known as buttress roots. Buttress roots are aerial extensions of the lateral surface roots and can be quite large, sometimes spreading 30 meters above ground and continuing underground. They provide additional support and are a common feature in many species, particularly those in wet, nutrient-poor soils.
Role of the Base
The root flare and buttress roots perform functions for a tree’s survival. This area anchors the tree in place, providing stability against forces like wind and storms. A well-developed root flare allows for root anchorage, reducing uprooting risk. Trees planted too deeply, with a buried root flare, can struggle with stability and may develop problems like stem girdling roots, which can compromise the tree’s support system.
The base also facilitates the transport of water and nutrients. The root flare acts as a central exchange point, moving water and minerals upwards. Sugars from the leaves are transported downwards to the roots. The extensive network of buttress roots aid nutrient absorption over a wider area, where nutrients are concentrated. This structure helps distribute the tree’s weight and resist stresses, promoting tree health and longevity.