Cocowood Fibrovascular Tissue System—Another Wonder of Plant Evolution

Abstract

The coconut palm (Cocos nucifera L.) stem tissue (referred to as cocowood in this study) is a complex fibrovascular system that is made up of fibrovascular bundles embedded into a parenchymatous ground tissue. The complex configuration of fibrovascular bundles along with the non-uniform distribution of the material properties likely allow senile coconut stems to optimize their biomechanical performance per unit mass (i.e., mechanical efficiency) and grow into tall, slender, and very flexible plants with minimum resources of biomass and water. For the first time, to the best of the authors' knowledge, this paper examines, from the integral (i.e., stem structure) and macroscopic (i.e., tissue structure) levels of hierarchy, the characteristic triple helix formation depicted by the fibrovascular bundles within the monocotyledon cocowood. The natural course of the tangential orientation of the axial fibrovascular bundles is mapped for the whole cocowood structure by quantifying 264 cocowood discs, corresponding to 41 senile coconut palms estimated to be >70 years old. The observed variations were modeled in this paper by simple equations that partially enabled characterization of the cocowood fibrovascular tissue system. Furthermore, 11 finite element analyses (FEA) were performed over a three dimensional (3D) finite element (FE) model resembling a characteristic coconut palm stem of 25 m in height to analyze the biomaterial reactions produced by the progressive deviation of the tangential fibrovascular bundles on the cocowood mechanical response (i.e., on the material compressive strength and the bending stiffness). The analyses in this study were carried out for the critical wind speed of 23 m/s (i.e., Gale tornado according to the Fujita tornado scale). For each analysis, the characteristic average maxima degree of orientation of the cocowood fibrovascular bundles was varied from 0° to 51°. The acquired results provided a deep understanding of the cocowood optimum fibrovascular tissue system that denotes the natural evolution of the material through millions of years. The knowledge advanced from this study may also serve as concept generators for innovative biomimetic applications to improve current engineered wood products.

Innovative Bio-composite Sandwich Wall Panels made of Coconut Bidirectional External Veneers and Balsa Lightweight Core as Alternative for Eco-friendly and Structural Building Applications in High-risk Seismic Regions

“…Within this context, the core shear strength of prototype panel 2 is in average 1.5 times greater than prototype panel 1, which in theory is correct as the lighter core section of the sandwich prototype panel 1 is about 1.2 times greater in volume than prototype panel 2, and consequently, it makes the latter prototype less vulnerable to shear stresses. Moreover, it confirms one important finding in [8][9][10][15][16][17][18] that states the mechanical properties in biomaterials are all quasi-linearly proportional to density. On the other hand, it is unfortunately not possible to establish any comparison between the resulting bending performances acquired in this study and conventional wall building elements (e.g.…”

“…These compressive MOR L results were expected as the thickness of the coconut external boards for both prototype panels varies by just 2 mm. The coco-veneer external boards with a fibre-like structure [15] are the denser part of the sandwich construction and, therefore, are meant to fully resist the progressive generation of compressive stresses. Accordingly, among the variables in Eq.…”

The 4-Dimensional Plant: Effects of Wind-Induced Canopy Movement on Light Fluctuations and Photosynthesis

“…The impact of wind on plants largely depends on speed, duration, and the extent to which wind can penetrate canopy layers. Sufficient wind speeds can affect plant development, form and function, resulting in reductions in leaf size, plant size (dwarfing), and damage to plant surfaces (Grace, 1977 , 1988 ; Ennos, 1997 ; Smith and Ennos, 2003 ; de Langre, 2008 ; Onoda and Anten, 2011 ). High winds can also cause stem breakage and lodging (Berry et al, 2004 ), affect insect activity and population growth and the development and dispersal of pests and diseases within cropping systems (Aylor, 1990 ; Moser et al, 2009 ; Shaw, 2012 ).…”

“…High winds can also cause stem breakage and lodging (Berry et al, 2004 ), affect insect activity and population growth and the development and dispersal of pests and diseases within cropping systems (Aylor, 1990 ; Moser et al, 2009 ; Shaw, 2012 ). Wind alters heat and mass transfer, for example, by increasing leaf transpiration rate through reduction of boundary layer resistance, and the airflow regulates the microclimate of the vegetation (Grace, 1977 , 1988 ; Brenner, 1996 ; de Langre, 2008 ). Moderate wind speeds can alter transpiration rates, indirectly affecting photosynthesis via changes in stomatal conductance and leaf temperature (Smith and Ennos, 2003 ) but this would be dependent upon the local environmental conditions.…”

“…For example, in a hot environment, increases in transpiration and concurrent decreases in leaf temperature could be beneficial, assuming water is not limiting. However, under other less favorable conditions, the impact of moderate wind speeds on boundary layers alone may not affect leaf photosynthesis rates significantly or could negatively affect them (Grace, 1988 ).…”