Centre for Biomimetics, University of Reading (UK)
Title: Fibre hierarchies in plants: the key to smart solutions
Plants do not have a nervous system and they do not have means of locomotion. These constraints mean that plants are dependent on specialised mechanisms for survival in their environments, static or dynamic. The mechanical design of plants, in particular, is to large extent controlled by the hierarchical organisation of cellulose fibres in the various cellular tissues and organs. Fibrous structures, even if based on only a few chemical compounds, can provide a virtually unlimited range of design solutions, tailored to specific performance levels and to specialised shape adaptation mechanisms. Exploiting the materials science and engineering of fibrous composites is indeed a key strategy of plants. This can be seen in “passive” systems, such as seedpods, where the “programmed” opening to release seeds is dependent only on the organisation of the tissues and on the response of the materials to changes in water content. The same physical/mechanical principles apply to the re-orientation of trunks and branches in trees, in combination with growth and modulation of tissue type in response to gravitropic or wind stimuli, at different scales of size and time. In “active” or “semi-active” systems such as leaf deployment, opening of petals, rapid movement (Mimosa pudica), etc. interactions with water (turgor pressure) as well as growth contribute significantly to the hierarchical organisation of the cellular structures involved, exploiting shape differentiation and geometrical anisotropy for “movement”, rapid or slow. These concepts will be illustrated with examples, focussing on the fundamental role played by the organisation of plant materials and structures to the development of smart solutions.
Contribution to the Workshop “Smart Solution from the Plant Kingdom”