Why do you think Taylor decided to take care of Turtle and "adopt" her rather then drop Turtle off at an orphanage/foster care?

The dominant relationship in the novel is between the mother and child; most of the female characters in The Bean Trees are mothers who raise their children without the help of an absentee father. Mama Greer raised Taylor as a single mother, and Taylor in return becomes a single mother when she gets custody of Turtle while traveling through Oklahoma. I think Taylor needs Turtle as much as Turtle needs her. They both fill a void in each other's lives.