The notion of polarity is often used in developmental biology for the explanation of various phenomena. Some authors have considered that polarity is absolutely essential for certain kinds of phenomena to appear. In this paper, we identify polarity of an individual cell with its ability to distinguish in somo sense between its ‘ left’ and its ‘ right’ side. We show, using a developmental model originally duo to Lindenmayer, that even if we restrict ourselves to models in which individual cells have no polarity, the models remain general enough to realize any effective procedure, in other words, they have a universal computing ability. Various special cases are considered, These results, as well as other results concerning regulation and synchronization in development, indicate that polarity is not a necessary con-copt, and may not even he an essential concept, for morphogenesis.