Hygroscopic movements in Geraniaceae: the structural variations that are responsible for coiling or bending

• DOI: 10.1111/nph.12254
• Publication Date: 2013-04-10T08:05:03Z
• Authors: Yael Abraham; Rivka Elbaum
• Keywords: Geraniaceae; Onagraceae; Microfibril

Summary The family Geraniaceae is characterized by a beak‐like fruit, consisting of five seeds appended tapering awn. awns exhibit coiling or bending hygroscopic movement as part the seed dispersal strategy. Here we explain variation in reaction based on structural principles. We examined representative species from three genera: Erodium , Geranium and Pelargonium . Using X‐ray diffraction, electron polarized light microscopy, measured cellulose microfibril angles relation to cell helix axes. behavior separated single cells during dehydration was also examined. A bi‐layered structure characterizes all genera studied, with hygroscopically contracting inner layer, stiff outer layer. found that arrangement layer responsible for type awn deformation (coiling bending). In examined, identified an additional sublayer, which adds divide movements into types: bending, coiling, coiled‐bending. All types are genus. These characteristics importance understanding evolution mechanisms family.