Recently, genetic algorithms and other newly developed search techniques have received a lot of attention, because of their easy to use nature in many engineering problems. They are capable of locating good approximates in extremely large search spaces with a reasonable amount of computational effort. This study is one of a series in which the optimization systems of plants are applied to the field of engineering. Plants have been adapting themselves to severe environmental conditions to survive and reproduce by using many optimization techniques. The leaf cellular automata (LCA) developed in this study are also one of the search algorithms inspired by the mechanisms of the reactions of a leaf. The basic calculation procedure is similar to that of conventional of cellular automata. In order to test the performance of this algorithm, a knapsack problem that is a typical combinational optimization problem was solved by LCA. LCA could be used to obtain a considerably better solution than random walks.