THEORETICAL BASIS
Stem Shearing Mechanics
A cross-section of stem consists of four elements:
epidermis, fiber, soft cells, and cavities. The epidermis is a
collenchyma, composed of long living cells, often
containing chlorophyll. The cell wall only thickens locally,
not disturbing local elongation growth. When the organs
form in the plant, the collenchyma is the first tissue that
provides mechanical support. The fiber has a light section
and a vascular bundle of thick-wall long cells. The soft
cells are larger cells that surround the fiber. The epidermis
and fiber are elements of material structure, providing the
stem with strength. The elasticity, strength and rigidity
inside the plant material are formed from the rheological
properties of the cell wall Mohsenin (1986).