You might have to do much of this lengthened writing yourself. I think that there is much here upon which to construct a strong answer, though. Melinda's rape and the experience of being shunned from society forced her to have to develop a new "voice." This voice had to be personal, originating from her own experience and authenticating what was endured. The nurturing of this voice, of what the new identify of Melinda would consist, revolved around nurturing and cultivating something that would be subject to the harshest of conditions in the world. It is in this light that the tree might be a good symbol to reflect this. There has to be significant tilling of the soil (enduring and setting up the personal isolation element) and establishing the correct conditions for it to grow, and then over time, personal cultivation and care is needed in order for it to grow, sprout leaves, fruit, flowers, and experience what it means to bloom (finding her voice through art and creative expression and confronting Andy in the hallway.) In the end, this is what Melinda has to undergo in order to establish her new voice and identity, where she experiences the power of being able to "speak."