There are many literary elements in this book, and the most powerful one, in my opinion, is the use of symbolism. I will share my ideas about some of these symbols.
The bees are, of course, a symbol of the need for community and a queen to lead the community. The quotation at the beginning of each chapter helps us to see what the bees symbolize in that particular chapter.
The Black Mary acts a symbol of motherhood, spirtuality, feminism, and enslavement. Remember she is said to have been able to escape the chains of slavery. She is an object of worship for the Daughters of Mary, a female "stand-in" for the mother of Christ. She also represents "heart," having a red one painted on her to symbolize love and pain. For Lily, she is a symbol of purity, since Lily cannot bring herself to touch Black Mary's heart until she has confessed to August the truth about her journey.
Water is a symbol in many different ways in the story. You will notice that when Lily and Rosaleen run away, they must cross a stream. This stream is a symbol of them moving on to a new place and life. Also, you will notice that their argument is resolved while they are in the water, thus making water a symbol of both renewal and harmony. There is a scene in the story in which June and Lily finally connect because both have been squirted with a hose. May, of course, dies in water, having weighed herself down with a stone. Thus water might bring death but peace to a troubled soul.
There are other symbols and other literary elements in this wonderful book, and I hope others will share some of their ideas.