The structure of a leaf has important implications for how it decomposes. Leaves are coated in a waxy cuticle that decomposers must get through before they can access the leaf cells. Each cell of a leaf has a primary cell wall, which is the main target of decomposition. The primary cell wall components are cellulose, hemicellulose, and lignin. Cellulose is a long chain, or polymer, of glucose molecules linked together to form a crystalline structure. Hemicellulose is a polymer of shorter chains of mostly xylose and arabinose molecules, with a branching structure that encases cellulose. The glucose, xylose and arabinose molecules are sugars, which are high-energy foods that microbes attack first in decomposition. Lignin is a complex polymer of different kinds of phenol-based molecules, arranged in random patterns that occupy spaces between the bundles of cellulose and hemicellulose. Lignin is a very low energy food that is attacked last.