If the trunk goes straight into the ground like a telephone pole, the part of the tree we need to see may be buried.
The root flare is where the trunk widens into the tree's main structural roots. On a properly planted tree, you should be able to see that widening at or very near ground level.
If the trunk stays the same width all the way into the soil, stop and look closer. The flare may be buried by deep planting, added soil, landscape beds, or years of mulch piled against the trunk.
A tree can look fine for years while trouble develops below grade. When the flare stays buried, roots can circle the trunk, bark can stay buried where it should be exposed, and the tree can slowly lose its ability to move water and nutrients the way it should.
“Three of the most common causes of poor tree establishment or death are planting too deep, improper watering, and girdling roots.”Texas A&M Forest Service, Tree Planting guidance
When a tree is thinning or declining and the canopy does not explain it, the root flare is one of the first places we look.
Sometimes the fix is simple. Sometimes uncovering the base reveals a bigger problem. We want to know which one it is before anybody starts cutting roots or moving soil.

Arborwise Tree Check walks you through what you can actually see and helps narrow down what deserves attention.