Plants are tiny computers. As they grow, the sprouts are computing from first principles how to be a plant. We’ll see how they do it! This talk uses Ruby and the ‘graphics’ gem to build models of all kinds of plants, from algae blooms to juniper branches. We’ll touch on rewriting systems, formal grammars, and Alan Turing’s contributions to botany. We’ll look at the shapes of euphorbia, artichoke, and oregon grape, and how these come from plants’ love of sunlight and greedy desire for growth. By the end, we'll have a series of great visual metaphors for fundamental computer science concepts!