Have you ever looked at a cross section of a tree? The rings provide a striking visual representation of the tree's development. When you look, you can see seasons of great growth and flourishing. But you can also see seasons where there appears to be almost no appreciable growth. Indeed, there are seasons of disease and infestation and fire that permanently scar the tree, yet often it continues to grow.
I think God gave us so much botanical imagery because he wanted us to understand that Christian growth is a lifelong process, marked by times of seemingly unrelenting growth, times of stagnation, and times of damage, but God, by His Spirit, continues to grow and mature His children.
I wrote this poem yesterday as I was thanking God for His persistence in my sanctification.
an acorn planted
becomes a mighty giant
...but not today