ROOT
- In dicotyledonous plants, the primary root emerges from the elongation of the radicle and extends into the soil.
- This primary root gives rise to lateral roots of varying orders, collectively known as secondary, tertiary, etc. roots.
- These primary roots and their branches collectively form the tap root system, exemplified by the mustard plant.
- In contrast, monocotyledonous plants exhibit a distinct root system.
Tap Root System (Dicotyledonous):
- Dicotyledonous plants display a tap root system where the primary root elongates directly from the radicle.
- This central root gives rise to lateral roots of different orders.
- The combined network of primary and lateral roots constitutes the tap root system.
- This structural arrangement is evident in plants like the mustard plant.
Fibrous Root System (Monocotyledonous):
- Monocotyledonous plants diverge from the tap root pattern.
- The primary root in these plants is short-lived and replaced by a multitude of roots that originate from the base of the stem.
- This intricate network of roots is referred to as the fibrous root system.
- The wheat plant serves as an exemplar of this arrangement.
Adventitious Roots:
- Certain plant species, such as grass, Monstera, and the banyan tree, deviate from the conventional root initiation from the radicle.
- Instead, they generate roots from various parts of the plant, unrelated to the radicle.
- These roots are termed adventitious roots and contribute to the plant's unique structural adaptation.
- Examples include grasses and the banyan tree.
Functional Roles:
The root system performs several vital functions for plants:
- Water and Mineral Absorption:
- Roots are responsible for absorbing water and essential minerals from the soil, which are indispensable for plant growth.
- Anchorage and Support:
- The root system ensures proper anchorage, stabilising the plant against external forces like wind and rain.
- Storage:
- Roots serve as reservoirs for storing reserve food materials that can sustain the plant during periods of nutrient scarcity.
- Plant Growth Regulation:
- Root tissues participate in the synthesis of plant growth regulators, contributing to overall growth and development.
Region of Root:
- Root Cap and Protection:
- The root apex is shielded by a protective thimble-like covering called the root cap.
- Root cap safeguards the tender tip of the root during soil penetration.
- Meristematic Zone:
- Situated above the root cap, a few millimetres away.
- Cells in this zone are small, thin-walled, and densely packed with protoplasm.
- These cells undergo repeated divisions, contributing to root growth.
- Region of Elongation:
- Adjacent to the meristematic zone.
- Cells in this region rapidly elongate and expand, promoting the root's lengthwise growth.
- Region of Maturation:
- Proximal to the region of elongation.
- Cells in this zone differentiate and mature, transitioning into specialised structures.
- Root Hairs and Nutrient Absorption:
- Emerge from the maturation zone, formed by epidermal cells.
- Root hairs are fine, thread-like structures.
- Function as absorptive extensions, enhancing water and mineral uptake from the soil.
Functions and Significance:
- Root Cap Protection:
Shields the delicate root apex from potential damage.
- Meristematic Activity:
Facilitates continuous cell division, supporting root growth.
- Elongation and Maturation:
Drives longitudinal growth and cellular specialisation.
- Root Hairs for Nutrient Uptake:
Efficiently absorb water and essential minerals from the soil.