L-systems, also known as parallel string rewriting systems, are named for Aristid Lindenmayer, who pioneered their employment in the field of botany at the University of Regina in Saskatchewan (Canada). They are a blending of various fields including computer science, linguistics, and genetics. In formal language theory, the simplest L-systems are classified as D0L, meaning deterministic 0-context (context-free); and replacement is in parallel. This means that each symbol in the string is replaced according to a fixed set of rules, regardless what the surrounding symbols may be, and all symbols in the string are replaced simultaneously at each step. A formal mathematical definition for L-systems was proposed in 1968 by Lindenmayer as basis for an axiomatic theory of biological development. They are used (as demonstrated below) for generating fractals, modelling plants, and simulating flower development (or patterns of inflorescence). Chomsky grammers (used in computer science) differ from L-systems in that the replacement rules (productions) are applied in sequence rather than all at once (the latter better simulating simultaneous cell divisions).