What would be the significance of having both Collenchyma & Parenchyma?

Answer 1

jeez.. long answer

in short: collenchyma gives the plant strength and support but also allows it to have certain flexibility. The parenchyma, on the other hand gives support, and also since it's highly meristematic it's very useful for healing. Depending on the type of parenchyma (aerenchyma or chlorenchyma) it can also be used for air exchange or photosynthesis.

So parenchyma and collenchyma play a major role in the support of the plant

Answer 2

The types of ground tissue found in plants develops from ground tissue meristem and consists of three simple tissues:

Parenchyma (have retained their protoplasm)
Collenchyma (have retained their protoplasm)
Sclerenchyma (have lost their protoplasm in mature stage, i.e. are 'dead')
Parenchyma
Parenchyma is the most common ground tissue, it forms e.g. the cortex and pith of stems, the cortex of roots, the mesophyll (photosynthetic cells), the pulp of fruits, the endosperm of seeds, and the photosynthetic areas of a leaf. Parenchyma cells are capable of cell division even after maturation (i.e. they are still meristematic). They have thin, but flexible, cell walls, and are generally cube-shaped and are loosely packed. They have large central vacuoles, which allows the cells to store nutrients and water.

Parenchyma cells have a variety of functions;

photosynthesis (may then be called Chlorenchyma /Mesophyll cells),
gas exchange (Aerenchyma),
storage,
secretion (e.g. Epithelial cells lining the inside of resin ducts)
healing
other specialised functions.

Collenchyma
Collenchyma tissue is composed of elongated cells with unevenly thickened walls. They provide structural support, particularly in growing shoots and leaves. Collenchyma tissue composes, for example, the resilient strands in stalks of celery. Its growth is strongly affected by mechanical stress upon the plant. The walls of collenchyma in shaken (to mimic the effects of wind etc) plants may be 40%-100% thicker than those not shaken. The name collenchyma derives from the Greek word "kolla", meaning "glue", which refers to the thick, glistening appearance of the walls in fresh tissues.

There are three principal types of collenchyma;

Angular collenchyma (thickened at intercellular contact points)
Tangential collenchyma (cells arranged into ordered rows and thickened at the tangential face of the cell wall)
Lacunar collenchyma (have intercellular space and thickening proximal to the intercellular space)
The Parenchyma consists of relatively large, thin-walled cells.
The cells are arranged loosely, that is, there are intercellular spaces among them. The protoplasts of these cells contain chloroplasts. Some of these cells may have amyloplasts and crystals. Pereskia is a member of the cactus family. It has spines but it also has normal leaves. Its flowers are extremely beautiful like those of most Cactaceae.

COLLENCHYMA

Collenchyma is closely related to parenchyma. However, the plastids are not well differentiated in collenchyma while they are well differentiated and obvious in parenchyma.

Collenchyma always occurs just beneath the epidermis, while parenchyma occurs throughout the plant.

Collenchyma cell walls are unevenly thickened. When the thickening occurs at the corners where cells are joined it is called angular. Lamellar collenchyma has thickenings on their tangential walls, which are parallel with the surface.

Lignin is usually not present in collenchyma.