Chapter 35: Vascular Plant Structure, Growth, and Development

Introduction to Vascular Plants

• Definition: Plants with a circulatory system to transport nutrients and water.
• Key Structures: Xylem and phloem.

Plant Organs and Systems

• Shoot System: Above ground, absorbs light and CO2.
• Root System: Below ground, absorbs water and minerals.
• Main Organs: Leaves, stems, and roots.

Roots

• Function: Anchor plant, absorb minerals and water, store carbohydrates.
• Primary Root: First to emerge from seed, branches to form lateral roots.
• Taproot: Main root, anchors plant, can store food.
• Lateral Roots: Perform absorption of nutrients.

Stems

• Function: Bear leaves and buds, support.
• Structure: Nodes (where leaves attach) and internodes (space between nodes).
• Buds:
  • Apical Bud: Located at shoot tip.
  • Axillary Buds: Can form branches, thorns, or flowers.
• Modified Stems: Rhizomes, stolons, tubers.

Leaves

• Function: Main photosynthetic organ, gas exchange, heat dissipation.
• Structure:
  • Blade: Flat part.
  • Petiole: Stalk that joins leaf to stem.
• Types of Leaves:
  • Simple Leaves: Single undivided blade.
  • Compound Leaves: Multiple leaflets.
• Modifications: Tendrils, spines, storage leaves, reproductive leaves.

Plant Tissues

• Types: Dermal, vascular, ground.
• Dermal Tissue: Outer protective covering (epidermis, cuticle, periderm in woody plants).
• Vascular Tissue: Xylem (water transport), phloem (sugar transport).
• Ground Tissue: Functions in photosynthesis, storage, support.

Types of Plant Cells

• Parenchyma Cells: Thin, flexible, metabolic functions, storage.
• Collenchyma Cells: Support young shoot parts, flexible.
• Sclerenchyma Cells: Rigid support, lignin-rich, dead at maturity.

Xylem and Phloem

• Xylem: Conducts water, made of tracheids and vessel elements.
• Phloem: Transports sugars, made of sieve-tube elements and companion cells.

Growth in Plants

• Primary Growth: Length; involves apical meristems.
• Secondary Growth: Thickness; involves lateral meristems (vascular cambium and cork cambium).

Secondary Growth in Trees

• Vascular Cambium: Adds layers of xylem (wood) and phloem.
• Cork Cambium: Replaces epidermis with tougher periderm.

ABC Hypothesis (Flower Development)

• Genes A, B, C: Control organ identity in flowers.
• Organs: Sepals, petals, stamens, carpels.

These notes cover the essential points on vascular plant structure, growth, and development. They serve as a foundational review for understanding plant biology in a vascular context, detailing the functioning of roots, stems, leaves, and their respective tissues and cells.