A baby tree is called an infant, just like a baby human. During this phase, the trees are very thin and small, and though many grow on their own, human interaction with care and attention can help them thrive.
There are seven total stages in the life cycle of a tree, and they mirror the stages of human life. The youth stage is the second stage, which is like the teenage years of a tree. This is followed by the prime of life and middle-aged years. Trees also go through a senior stage as well as a twilight stage. The final stage of a tree's life, just like a human's life, is death.