Theme III.b: Micromorphological characteristics of plant drugs (vegetal drugs, herbal drugs)
Without certain strength, the plant could not retain its typical shape, which is necessary for the development of its vital activity.
Most plants determine its strength and elasticity to the presence of special mechanical tissues, formed by cells arranged in compact masses and with a strong thickened membrane.
If the membrane is thickened in part, the tissue formed is the collenchyma, if the membrane is completely thickened, the tissue formed is the sclerenchyma.
In the sclerenchyma, thickening can reach such extremes that cell volume is reduced to almost nothing and in this process could die the protoplasm.
It´s in the plant parts that still develops active growth and is found exclusively as supporting tissue, it´s a living tissue which can grow and expand
It is always of primary origin and their membranes are only partially thickened.
It performs in adult plant organs, a function equivalent to that performed in the collenchyma plant parts that still grow.
According it has to resist to pressure or traction, the mechanical tissue consists of "stone cells", with thick wall or sclerenchyma fibers, elongate and thickened membrane.