Root & Shoot Studies 2
Modification of root:
Tap root of the plant
some time modified for performing certain specialized functions as enlisted
below.
·
Tap roots of carrot, turnip and adventitious roots of sweet potato get
swollen and store food.
·
Hanging structures that support a banyan tree are called prop roots. Similarly, the stems
of maize and sugarcane have supporting roots
coming out of the lower nodes of the stem. These are called stilt roots.
·
In some plants such as Rhizophora, growing in swampy areas, many roots
come out of the ground and grow vertically upwards. Such roots, called pneumatophores, help to get oxygen for
respiration.
Morphology and growth of Root:
Roots grow in length only
from their ends. The very tip of the root is covered by a root cap, which
serves to protect the growing tip as it makes its way through the soil. Just
behind the root cap lies the apical meristem, a tissue of actively dividing
cells. Some of the cells produced by the apical meristem are added to the root
cap, but most of them are added to the region of elongation, which lies just
above the meristematic region (fig 3). It is in the region of elongation that
growth in length occurs. Above this elongation zone lies the region of
maturation, where the primary tissues of the root mature, completing the
process of cell differentiation that actually begins in the upper portion of
the meristematic region.
Anatomy of root:
When dissected, the arrangement
of the cells in a root is root hair, epidermis, cortex, endodermis pericycle
and vascular tissue (from outer to inner) in the centre of a root to
transport the water absorbed by the root to other places of the plant.
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