In William Blake's "A Poison Tree," what does the persona compare himself to?

In William Blake's "A Poison Tree," published in 1794 in his Songs of Experience, the persona compares his anger, or "wrath," to a tree, and compares himself to a sort of gardener (2). In the first stanza, the persona reveals that he was once angry with his friend, but he "told [his] wrath," or discussed the issue, and the issue was resolved (2). However, the persona then reveals that he was once angry with his enemy, but failed to resolve the issue. Because of this, his wrath "grows." In the second stanza, he "waters" and "suns" his anger, much like one would water and provide sunlight for a tree (5,7). The tree then bears an apple, and the foe steals into the persona's garden, eats the apple, and is later found dead. With these descriptions, Blake uses figurative language, specifically metaphor, to compare the emotion of anger to a tree. Moreover, since the persona cares for the tree, he is compared to a gardener. For Blake, anger is a "poison tree", for if our animosity with others remains unchecked, it will grow, and may lead to unintentional, destructive deeds.