We introduce in this paper an interface for botanical tree modeling that allows the user to sketch a tree, and then to automatically reproduce it at various stages of 'growth'. The technique works by first inferring as best as possible the L-System growth rule that represent the tree model drawn by the user. The user can then reproduce the tree model by drawing a growth stroke.The growth stroke indicates the shape of the main axis, and the height up to which the tree should be grown, and determines the number of iterations of applications of the L-system rule. We show in this paper how the technique can be used as a simple yet effective way to produce variants of a tree structure. © 2010 Springer-Verlag Berlin Heidelberg.