The different parts of root and types of roots are discussed below.
PARTS OF A TYPICAL ROOT
If we study a root from its tip upward we find the following parts :
1. Root Cap : At the apex of the root is present a smooth cap shaped structure called root cap. Is (screw pine). In hydrophytes instead root cap the root cap is multiple in Pandanus (screw pine). In hydrophytes instead of root cap a root pocket is present e.g., Pistia Lemna.
2. Zone of cell formation (meristematic zone) : The cells in this region are in active state of division and thus their number increases continuously. Cells of this region are in walled with dense cytoplasm and large nucleus. Either there are no .vacuoles or the size of vacuoles is much reduced in these cells.
3. Zone of cell elongation : This region is situated, just above the meristematic zone. In cells of this zone large number of small vacuoles develop and later these vacuoles fuse to form one large central vacuole filled with cell sap. In this region the cells are elongated.
4. Zone of cell maturation (= differentiation) : This region is found just above the zone of cell elongation. The cells in this region are differentiated into permanent tissues depending upon the functions they have to perform. In some cells special type of thickening develops e.g., Xylem trachejds and trachea. Outermost layer of cells in this region develops root hair.
TYPES OF ROOTS
Roots are of two types :
2. Adventitious roots.
1. Tap roots : These roots are usually found in dicotyledons and are formed by the continuous growth of radicle. They can branch forming secondary and tertiary roots. Taken together they are called tap root system.
2. Adventitious roots : These roots are usually found in monocotyledons. In these plants the radicle dies immediately after germination of seeds and later these roots arise from any other portion of the plant e.g., From stem in maize or from leaves in Bryophyllum. Taken together such roots are called fibrous root system\