Symbols in The Bean Trees enrich the themes found in the novel and, oftentimes, suggest Kingsolver's extensive background in biology.
A symbol functions literally as a concrete object and figuratively as a representation of an idea. Symbols allow writers to compress complicated ideas or views into an image or word. Some symbols, such as a dove as a representation of peace or winter as a representation of death, are well known; they are called public symbols. Many times, writers invent their own symbols. When Kingsolver creates symbols, she has her own definite meanings for the symbols. However, because each symbol has a myriad of interpretations, she prefers that her readers interpret the symbolism as it relates to their own life experiences.
Much of the symbolism found in the novel is biological in nature, as Kingsolver repeatedly employs birds, plants, and animals. For example, the symbiotic relationship between the rhizobia and the wisteria vines represents the theme of the interdependency between people in a community. The "bean trees," or wisteria, that are able to thrive in non-fertile soil and the bird that builds its nest in a cactus ("You just couldn't imagine how she'd made a home in there") may symbolize the resiliency and ability to thrive that human beings (like Turtle) possess.
A bird is used as a symbol again later in the novel. After Turtle is molested in the park, a bird gets trapped in the house and, with Taylor's help, is freed. This trapped bird symbolizes the fact that Turtle is once again trapped within herself — she stops speaking and has a glazed look in her eyes — but with Taylor's help, Turtle is freed, too. This symbol reinforces the themes of interdependence between people, the importance of family, and hope for the future.
