A skeleton with several scales of porosity
The wood of Cylindropuntia imbricata forms a network of connected bands surrounding elongated openings. At the larger scale, the skeleton's spatial arrangement is visible. At the smaller scale are tissues composed of vessels, fibres and wood rays. Finer discontinuities consist of cell lumina and pits in their walls. Each scale contributes a different trait to the material's organisation. [Morankar et al. 2024]
What was studied in the laboratory
Morankar and colleagues used dry wood supplied from New Mexico, seasoned for at least two years. X-ray tomography revealed spatial structure, electron microscopy showed cell details, and nanoindentation allowed the local response of walls to pressure to be studied. Computational models compared selected porosity arrangements. [Morankar et al. 2024]
Fibres and rays differed in mechanical properties. In the dry material studied, fibres were stiffer in local measurements. This relationship relates to cell type, wall organisation and loading direction. Parameters obtained from the dried skeleton characterise material after loss of the stem's living, hydrated tissues. [Morankar et al. 2024]
Directions in wood
Elongated vessel elements connect to form axial transport pathways. Rays run transversely to the stem axis, and thick-walled fibres help support the structure. Their relative positions are superimposed on the larger scale of openings and bridges in the whole skeleton. [Morankar et al. 2024]
| Structural scale | Visible elements | Scope of information |
|---|---|---|
| Stem skeleton | Openings and connected wood bands | Geometry of the whole structure |
| Tissues and cells | Vessels, fibres, rays | Direction and type of wood organisation |
| Cell wall | Layers and pits | Local structure and response to pressure |
Anatomy leads to questions about function
In a living plant, wood participates in both transport and stem support. The paper described studies its structure and material mechanics in detail. The authors consider the relationship between vessel shape, water balance and resistance to flow disruption as an anatomical interpretation requiring additional hydraulic measurements in living tissues. [Morankar et al. 2024]
The openwork skeleton also inspires porous engineered structures. Such comparisons can vary opening size and connection arrangement separately to assess loading response. However, the biological reference remains a multilevel structure. The properties of a small wall sample, a wood band and an entire stem concern different scales. [Morankar et al. 2024]
Prepared from scientific publications. Names follow POWO. Historical names are given in discussions of older papers.
Cholla cactus wood (Cylindropuntia imbricata): Hierarchical structure and micromechanical properties
Morankar S., Luktuke A., Nieto-Valeiras E., Mistry Y., Bhate D., Penick C. A., Chawla N., Cholla cactus wood (Cylindropuntia imbricata): Hierarchical structure and micromechanical properties, Acta Biomaterialia, 2024, 174:269-280, doi: 10.1016/j.actbio.2023.12.005
Tomography, microscopy, nanoindentation and modelling of dry Cylindropuntia imbricata wood. The study describes structure from the openings in the skeleton to cell walls, and compares the properties of fibres and wood rays.
