root
DESCRIPTION
Root. The root is the organ of a plant that typically lies below the surface of the soil. Root is the organ of the plant, originates from the radical of the embryo. The first root that comes from a plant is called the radicle. - PowerPoint PPT PresentationTRANSCRIPT
Root
The root is the organ of a plant that typically lies below the
surface of the soil.
Root is the organ of the plant, originates from the radical of
the embryo.
The first root that comes from a plant is called the radicle.
It grows downwards, fixes the seedling later the plant to the
ground and absorbs raw food materials the soil
Characteristics
• Root does not normally bear buds.
• Root end is protected by a cup or thimble known as root cap.
• Root bears unicellular hairs, while the stem bears mostly
multicellular hairs.
• Nodes and internodes are absent in roots.
Functions
• Mechanical. eg. Anchorage• Physiological. eg.
• Absorption• Conduction• Storage mainly.
Types of Roots
• Normal Root
• Adventitious root / Fibrous root
Modifications of roots
Modified tap root
Fusiform rootSwollen in the middle and gradually tapering both ends. eg. Radish
Napiform rootThe upper part becomes almost spherical and sharply tapering at the bottom part. eg. Turnip.
Conical rootWhen the root is broad at the base and it gradually tapper towards the apex like a cone, it is said to be conical. eg. Carrot.
Tuberous rootWhen the root is thick and fleshy but does not maintain any particular shape, it is said to tuberous or tubercular. eg. Sweet potato
Modifications of rootsModified adventitious roots
Fasciculated root
When several tubercular roots occur in a cluster or fascicle at the base of
the stem are said to be fasciculate as in Dahlia and Asparagus
Moniliform root
When there are some swellings in root at frequent intervals, it is said to be
moniliform root. eg. Teasel gourd
Nodal root
When the slender root becomes suddenly swollen at or near the apex, it is
said to be nodal root. eg. Sugar cane
Epiphytic root
There are certain plants, commonly orchids, which grow on branches
of trees. Such plants are known as epiphytes.
In stead of sucking roots they develop special kinds of aerial roots
which freely in the air.
Each hanging root is surrounded by a spongy tissue, called velamen
with help of the velamen they absorbs moisture from the surrounding
air.
Modifications of roots