  The generation of anisotropic shapes occurs during morphogenesis of almost
all organisms. With the recent renewal of the interest in mechanical aspects of
morphogenesis, it has become clear that mechanics contributes to anisotropic
forms in a subtle interaction with various molecular actors. Here, we consider
plants, fungi, oomycetes, and bacteria, and we review the mechanisms by which
elongated shapes are generated and maintained. We focus on theoretical models
of the interplay between growth and mechanics, in relation with experimental
data, and discuss how models may help us improve our understanding of the
underlying biological mechanisms.
