1. Istituto Italiano di TecnologiaCenter for Micro-BioRobotics Viale Rinaldo Piaggio 34 Pontedera Pisa 56025 Italy
2. Plant Biomechanics GroupBotanic GardenFaculty of BiologyUniversity of Freiburg Schänzlestraße 1 Freiburg 79104 Germany
3. Cluster of Excellence livMatSFreiburg Center for Interactive Materials and Bioinspired Technologies (FIT)University of Freiburg Georges-Köhler-Allee 105 Freiburg 78110 Germany