Researches into Structure and Motion of Plants from Mechanical View Point

Abstract

In the past two or three decades, I have studied a number of topics concerning plant biomechanics or plant biomimetics, such as structure of folding paper observed in leaves and flowers of plants, folding storage and unfolding manner observed in Sensitive Plant, mechanical functions of sepals and petals observed in lily flower bud, vein structure and mechanical properties of a leaf of Santa Cruz Water Lily, mechanical behavior of tendrils with spiral structure supporting cucumber body, adherence in the column of Stylidium caesupitosum and high speed rotation ... etc. From these researches, several interesting ideas or mechanisms adopted by plants have been clarified. For examples, the unfolding vein angle of regularly corrugated simple leaves is chosen as satisfying smooth and earlier unfolding with relatively small energy, the thick main veins of giant water lily have the cross-section with a tear drop shape including many voids to accomplish simultaneously a large bending rigidity and a body as light as possible, very complicated closing motion of a sensitive plant (Mimosa pudica) leaflet can be carried out by a simple rotation of a small pulvinus and a combination of a few installation angles of leaflet on the mid rib, or the incredibly rapid rotation of Stylidium flower column may be performed by the quick release of strain energy stored in a bending part of column. A number of interesting topics are shown here.