The poem compares anger to a tree using a metaphor. A tree is compared to a person's emotions in the poem. The poem makes use of metaphor, which is a comparison of two things. The tree is transformed into a metaphor for the fury. The poem expresses the speaker's rage. It does so by comparing his anger to a tree. Poison is something that can harm you even if you don't see it. In this case, the tree is considered poisonous because it produces sharpened tips at its leaves where the bird should rest or sleep. These tips are able to kill them if they touch them. The tree is dangerous because it may seem harmless but it can still hurt you if you try to sleep under it. Another figure of speech used in the poem is allusion. An allusion is when one thing refers to another thing that is already known. In this case, the tree is referring to the anger that lies within him. He who bears bitter fruits shall also bear bitter seeds. This quote from Jesus is what the tree represents in the poem. It says he who lives by hatred will die by hate. That means those who live their lives with anger will die with anger too. The tree is also saying that anger will consume you. It will make you feel bad about yourself and cause problems in your life. You should not be angry about anything else other than yourself if you want to solve any issues you might have.