Plant Tissues Lecture by Miss Angus

Introduction

• Focus on plant tissues
• Identifying plant tissues effectively for exams
• Functions and microscopic appearance of plant tissues
• Suitable for Life Sciences, grades 10 to 12

Types of Tissues

1. Meristematic Tissue

   • Temporary, found in growth regions
   • Types:
     • Apical Meristems: tips of shoots and roots, responsible for primary growth (lengthening)
     • Lateral Meristems: found in the stem, responsible for secondary growth (thickening)
   • Cambium: ring of tissue for growth in width, crucial for stump and bark formation

2. Permanent Tissue

   • Longer-lasting, derived from meristematic tissue
   • Types:
     • Epidermis
       • Protective layer, contains cuticle (prevents water loss)
       • Specialized cells: Stomata and Guard Cells (regulate gas exchange), Root Hair Cells (increase surface area for nutrient absorption)
     • Ground Tissues
       • Parenchyma
         • Most abundant, thin cell walls, intercellular airspaces
         • Functions: packaging, storage, gaseous exchange, and allowing water movement
       • Collenchyma
         • Thickened cell walls at corners, provides support
         • Functions: flexibility, support, green stems for photosynthesis
       • Sclerenchyma
         • Uniformly thickened walls, non-living
         • Functions: rigidity, strength
         • Types:
           • Fibers: found in wood and bark
           • Sclereids: found in nuts and stone fruit pits
     • Vascular Tissues
       • Xylem
         • Transports water and minerals in one direction (roots to shoots)
         • Long, thin, large lumen cells, thickened walls with lignin
         • Vessels vs. Tracheids
       • Phloem
         • Transports sugars in two directions
         • Sieve plates, companion cells for nutrient support

Conclusion

• Summary of plant tissues: Meristematic and Permanent (Epidermis, Ground, Vascular)
• Importance of understanding structure and function in plant biology