Plant Structure and Growth

Overview of Plant Structure and Growth

• Plants consist of cells that share general features.
• Plants have shoot (above ground) and root (below ground) systems that perform integrated functions.
• Meristems produce new tissues throughout a plant's life, responsible for both height and girth growth.

Types of Flowering Plants

• Monocots: One cotyledon (e.g., grasses, lilies).
• Eudicots: Two cotyledons (e.g., poplars, roses).
• Grouping based on growth type and lifespan:
  • Annual: One growing season (herbaceous).
  • Biennial: Two growing seasons.
  • Perennial: Continue growing year after year.

Plant Structures

• Plant Body: Dendritic form (spreading and branched).
• Shoot System:
  • Contains stems, leaves, buds, flowers.
  • Adaptations for photosynthesis and pollination.
• Root System:
  • Grows below the ground.
  • Functions to anchor, absorb water and minerals, store carbohydrates.

Plant Cells

• General features:
  • Primary cell wall surrounding plasma membrane.
  • Cellulose fibers in a hemicellulose matrix (rigid but flexible).
  • Cytoplasmic connections through plasmodesmata.
• Secondary Cell Wall (in some types):
  • Contains lignin, stronger, creates waterproof barriers.

Tissue Systems

• Dermal Tissue: Protects surfaces, contains epidermis.
• Ground Tissue: Simple structure with specialized functions:
  • Parenchyma: Photosynthesis, storage.
  • Collenchyma: Flexible support.
  • Sclerenchyma: Rigid support and protection (sclereids, fibers).
• Vascular Tissue:
  • Xylem: Conducts water and minerals (dead when functional).
  • Phloem: Conducts sugars, living cells.

Growth Pattern

• Indeterminate Growth in Plants:
  • Continuous growth driven by meristems.
  • Growth increases number and size of cells.

Primary Growth

• Increases height and root length from apical meristems.

Secondary Growth

• Increases diameter through lateral meristems (cork and vascular cambium).