The ringtree of Victoria is a fictional tree created by Ursula K. LeGuin in her science fiction book called The Eye of the Heron. As the ringtree grows, its beautiful flowers are fertilized and develop into seeds. All but one of these seeds falls to the ground and dies. The one remaining seed, a hard shelled, bitter tasting dark seed kills the tree as it ages. Then one day the seed explodes violently and creates a perfect ring of seedlings around it. These seedlings grew into new ringtrees, which created new tree rings, intertwined in fertile ground, and the cycle continued.
This tree can be looked at as a symbol for political change and societal growth. New ideas, often revolutionary can kill the society from which they developed. These new concepts are often hard and bitter and not very appealing, but when they mature, they can explode and spawn other ideas and ways of thinking. This is exactly what this book is about. It's a story about an oppressed people breaking free and seeking a new way of living.
Ursula LeGuin uses imagery and symbolism very effectively in her books and short stories. I was first introduced to her use of symbols in a short story class in college. Since then I've read all her writings looking closely for images and symbolism and have never been disappointed. Her short story The Ones Who Walk Away From Omelas is my favorite piece of literature, and the best use of symbolism that I've seen yet.