Overview
This lecture covers the main types of plant cells, their specialized functions, and how they combine to form tissues that support plant structure and health.
Types of Plant Cells
- Plant cells are eukaryotic and contain a nucleus.
- Sclerenchyma cells provide structural support; contain lignin for rigidity and are dead at maturity.
- Two types of sclerenchyma: fibers (long, slender, interlocking) and sclereids (shorter, irregular, thick walls).
- Collenchyma cells are elongated, support new growth, and are found in areas needing flexibility (e.g., celery stalks).
- Parenchyma cells are thin-walled, large, with a central vacuole and various plastids for metabolic functions.
- Parenchyma performs photosynthesis, stores carbohydrates and water, and can differentiate for repair.
- Xylem cells transport water from roots to leaves; these cells are dead at maturity.
- Phloem cells transport sugars and materials from leaves to roots; these cells are alive at maturity.
Plant Tissue Types
- Dermal tissue forms the outer protective layer, prevents water loss, and defends against pathogens.
- Vascular tissue consists of xylem and phloem for long-distance transport of water and nutrients.
- Ground tissue makes up most of the plant body, providing storage and structural support.
Key Terms & Definitions
- Sclerenchyma — hard, lignin-rich cells providing rigidity, dead at maturity.
- Collenchyma — elongated cells providing flexible support to new growth.
- Parenchyma — thin-walled, versatile cells for storage, photosynthesis, and repair.
- Xylem — vascular tissue transporting water, composed of dead cells at maturity.
- Phloem — vascular tissue transporting sugars, composed of living cells at maturity.
- Dermal tissue — outer protective cell layer.
- Vascular tissue — transport system (xylem and phloem).
- Ground tissue — tissue for storage and support within the plant.
Action Items / Next Steps
- Review examples of each cell and tissue type in different plants.
- Study diagrams of plant tissue organization for visual understanding.