Plants
Plants are the main motif of the autobiography. The author describes her research of the plants, but also relates processes of plant life to those of human life. Striking is the research the author described at the end, where she experimented with a group of same plants, and one of those plants was different from the others in the growth and movement of leaves, almost as if it's consciously trying to move, unhappy with its existence, in which the author finds and relates her own struggles.
The lab
The lab is a symbol of home and comfort to the author. She describes is it as a place where the lights are always on, a place where she puts her brain out on her fingers, a place where she moves, where it matters if she gets hurt, etc.
Opal
The author made a discovery that the seeds of hackberry trees are wrapped in opal. This discovery makes her realize her purpose and makes it all worthwhile. Later on, she describes her son as another opal, because he gave her a new meaning and new purpose she never quite believed she had.
