The most sensitive part of the tree, according to the speaker of the poem, is its roots. They contain the "strength of the tree" and its source, "white and wet," which have been hidden inside the dark and nourishing ground for years. The speaker has already identified the parts of the tree above-ground as being quite capable of healing themselves, saying that causing pain to the tree's bark, hacking away at it for example, will not kill the tree. The bark will heal and sprout new "Miniature boughs" that will grow and thrive. No, he says, the root has to be pulled out of the "anchoring earth" and made vulnerable. Then, it becomes an easy thing to kill the tree, allowing the roots to scorch in the sun, brown, harden, and wither. That being done, the tree's life will come to an end.