A model is proposed for root waving in the roots of Arabidopsis seedlings that takes into account background and mutagenized genetic variation, the physical interactions between root and gel surface, the kinematics of root growth, and the underlying chiral twisting tendency exhibited by the root tip. The model is an improvement over previous work in its explicit introduction of the affect on wavy growth of the physical milieu, which is a critical causal factor in any developmental system. Experimental and theoretical results are discussed.

Key words: Arabidopsis, development, root, wavy