With regard to our recent Opinion article (Computational morphodynamics of plants: integrating development over space and time. Nature Rev. Mol. Cell Biol. 12, 265–273 (2011))1, we thank Álvarez-Buylla and colleagues for their correspondence (Mutually reinforcing patterning mechanisms. Nature Rev. Mol. Cell Biol. 23 Jun 2011 (doi:10.1038/nrm3079-c1))2 and for letting us know of the addition that they have made (of a redundant WEREWOLF (WER) activating factor, MYB23)3 to their model of epidermal pattern formation in response to the experimental evidence on WER expression discussed by Savage et al.4. This underlines a central point of our article: that iteration between computational models and experimental tests can lead to new or modified models that better predict experimental results.