NEET High-Yield Chapter: Anatomy of Flowering Plants focuses heavily on the internal structure and functional tissue systems of plants. NCERT lines are directly asked in NEET—use this guide to revise thoroughly with key definitions and structural differences.
1. Plant Tissues
Plant tissues are broadly categorized into two main groups based on their capacity for cellular division: Meristematic Tissues and Permanent Tissues.
A. Meristematic Tissues
Active zones of continuous cell division, sub-classified by their location:
- Apical Meristem: Located at the absolute shoot and root tips; responsible for primary elongation.
- Intercalary Meristem: Positioned at the nodes (e.g., in grasses); allows regeneration of parts removed by herbivores.
- Lateral Meristem: Comprises the cambium layers; responsible for secondary growth, increasing the plant's girth.
B. Permanent Tissues
Mature cells that have lost the capacity to divide, split into two structural formats:
Simple Permanent Tissues (Homogeneous Cells)
- Parenchyma: Living cells, thin-walled, primary site for photosynthesis and storage.
- Collenchyma: Provides mechanical support, characteristically thick at corners due to cellulose/pectin deposits.
- Sclerenchyma: Dead cells at maturity with highly thickened, lignified walls.
Complex Permanent Tissues (Heterogeneous Cells)
- Xylem: Conducts water and minerals. Made of tracheids, vessels, xylem fibers, and living xylem parenchyma.
- Phloem: Translocates organic food. Made of sieve tubes, companion cells, phloem fibers, and phloem parenchyma.
2. Tissue Systems
Plants feature three major integrated tissue systems working in tandem:
| Tissue System | Primary Components & Characteristics |
|---|---|
| Epidermal System | Outer protective covering containing epidermal cells, guard cells (stomata), and appendages like trichomes or root hairs. |
| Ground System | Forms the main bulk of the plant body. Dominated by parenchyma, collenchyma, and sclerenchyma; active in photosynthesis and storage. |
| Vascular System | Consists of complex tissues (Xylem + Phloem) arranged in various structural patterns (radial, conjoint, open, or closed bundles). |
3. Anatomy of Dicot and Monocot Root
Dicot Root (e.g., Bean)
- Vascular arrangement: Alternate radial bundles, containing fewer xylem bundles (diarch to tetrarch).
- Secondary Growth: Active cambium ring forms, allowing regular secondary growth.
Monocot Root (e.g., Maize)
- Vascular arrangement: Polyarch condition with numerous xylem bundles.
- Internal structure: Central pith is large and well-developed; no secondary growth takes place.
4. Anatomy of Dicot and Monocot Stem
Dicot Stem
Vascular bundles are arranged symmetrically in a distinct ring structure. These bundles are conjoint, collateral, and **open** (possess intrafascicular cambium), making secondary growth fully possible.
Monocot Stem
Vascular bundles are characteristically scattered throughout the ground tissue. These bundles are conjoint, collateral, and **closed** (lack cambium), meaning no secondary growth can occur.
