Ch 28 Notes

Chapter 28: Plant (Angiosperm) Structure and Growth

Overview of Angiosperms

  • Angiosperms are divided into two major clades:

    • Monocots

    • Eudicots

Key Differences: Monocots vs. Eudicots

  • Cotyledons:

    • Monocots: 1 seed leaf

    • Eudicots: 2 seed leaves

  • Flower Parts:

    • Monocots: Typically multiples of 3

    • Eudicots: Typically 4, 5, or multiples thereof

  • Stem Vascular Bundles:

    • Monocots: Scattered

    • Eudicots: Arranged in a ring

Plant Structures and Functions

Plant Tissues and Cell Types

  • Types of Plant Cells:

    • Parenchyma: Most common, performs metabolic functions, has thin and flexible walls, large vacuoles.

    • Collenchyma: Unevenly thickened walls, provides flexible support.

    • Sclerenchyma: Rigid due to thick secondary walls containing lignin; provides structural support.

    • Xylem: Water-conducting cells; includes tracheids and vessel elements.

    • Phloem: Sugar-conducting cells; transports sugars through sieve-tube elements.

Plant Organs

  • Roots: Anchors the plant, absorbs water and minerals, stores carbohydrates.

  • Stems: Support leaves and transport materials between roots and leaves.

  • Leaves: Main site of photosynthesis; typically flattened with a petiole to connect to the stem.

Types of Growth

  • Indeterminate Growth: Continuous growth throughout the plant's life (enabled by meristems).

  • Determinate Growth: Growth that stops after reaching a certain size.

  • Primary Growth: Elongation of shoots and roots at apical meristems.

  • Secondary Growth: Increase in thickness in woody plants due to lateral meristems.

Plant Life Cycles

  • Annuals: Complete life cycle in one year or less.

  • Biennials: Require two growing seasons to complete their life cycle.

  • Perennials: Live for multiple years.

Plant Organization

Cells and Tissues

  • Cell: Smallest unit of living organisms; includes multiple types:

    • Parenchyma, Collenchyma, Sclerenchyma

  • Tissue Types:

    • Dermal: Protective outer covering.

    • Vascular: Conducts nutrients and provides support.

    • Ground: Filler that carries out various functions.

Organ Systems

  • Root System: All roots of the plant.

  • Shoot System: Contains stems and leaves.

Modified Structures

  • Roots: Adaptations for nutrient absorption, energy storage, or support; e.g., mycorrhizal associations, pneumonia roots, storage roots.

  • Stems: Rhizomes and tubers serve for vegetative reproduction and food storage.

  • Leaves: Tendrils for support, spines for defense, and storage leaves.

Meristems and Growth

Types of Meristems

  • Apical Meristems: Located at tips of roots and shoots.

  • Lateral Meristems: Increase the thickness of woody plants (vascular and cork cambium).

Tissue Growth

  • Primary Growth of Roots: Occurs in three zones:

    • Zone of Cell Division

    • Zone of Elongation

    • Zone of Differentiation

  • Secondary Growth: Involves vascular cambium and cork cambium, developing wood and bark.

Vascular and Bark Systems

Vascular Tissue

  • Xylem: Conducts water upwards; includes tracheids and vessel elements.

  • Phloem: Transports sugars and organic substances downward and throughout.

Bark

  • Consists of: All tissues outside the vascular cambium, including periderm.

  • Lenticels: Allow gas exchange between external air and living tissues.

Leaf Anatomy

Structure of Leaves

  • Epidermis: Outer layer, includes stomata for gas exchange.

  • Mesophyll: Ground tissue for photosynthesis, separated into palisade (upper) and spongy (lower) mesophyll.

  • Veins: Function in nutrient transport and structural support.

Leaf Venation Patterns

  • Monocots: Parallel venation.

  • Eudicots: Branched or netted venation.

Summary of Plant Structure and Growth

  • Understanding the anatomical and physiological characteristics of monocots and eudicots is vital for recognizing plant functions and adaptations in diverse environments.