Woody plants are perennials that create stiff structures above ground that they use throughout their lives. They all develop an inner "backbone" - wood - for support and a tough outer "skin" - bark - for protection. This strategy allows them to get closer to the sun. All plants are in competition with each other for sunlight, which is the energy source that they capture to power photosynthesis within their cells. Any plant that can grow taller than its neighbors will be more successful in this competition. Many woody plants have a range of attributes - lovely flowers, colored leaves, attractive barks.