Leaf Anatomy and Plant Cell Structure

Leaf Anatomy

• Cytology is the scientific study of cells, the basic unit of living organisms.
• Plant cells are characterized by a cell wall surrounding the plasma membrane, enclosing the cytoplasm where organelles reside.
• The cytoplasm and nucleus together form the protoplasm, with the nucleus containing the hereditary material.
• Plant cells possess characteristics differing from other eukaryotic cells, including a cell wall made of cellulose, hemicellulose, pectin, and lignin (unlike chitin in fungi or peptidoglycan in bacteria).
• Plastids, large vacuoles, and plasmodesmata connecting neighboring protoplasts are unique features.
• Plant anatomy, also known as micromorphology and plant histology, examines the microscopic structure of cells, tissues, and organs.
• A group of cells with identical form and function is called a tissue.
• Plant tissues are categorized into dermal, ground, and vascular tissues.

Dermal Tissues

• Dermal tissues cover plant surfaces and consist of epidermal cells, stomata, and trichomes (hairs).
• Epidermal cells form a single layer with no intercellular spaces.
• Cell shapes and arrangements vary across plant species.
• A waxy cuticle (made of cutin) covers epidermal cells, providing water impermeability.
• Cuticle characteristics (smooth, warty, or striated) vary.
• Upper and lower epidermis differ structurally.

Stomata

• Stomata are pores in the epidermis enabling gas exchange.
• They typically consist of a pair of guard cells surrounding a pore (ostiole).
• Stomata are found on both surfaces or solely on the lower surface.
• Subsidiary cells surround the stomata; their arrangement types are identified below.

Stomata Types

• Anomocytic (Ranunculaceous): subsidiary cells are similar in size.
• Anisocytic (Cruciferous): three unequal-sized subsidiary cells surround the stoma.
• Paracytic (Rubiaceous): two subsidiary cells with long axes parallel to the pore.
• Diacytic (Caryophyllaceous): two subsidiary cells with long axes perpendicular to the pore.

Trichomes (Hairs)

• Trichomes are outgrowths of epidermal cells in various shapes and sizes.
• Short, conical trichomes are called papillae.
• Long trichomes protect plants.
• Trichomes are classified into glandular and non-glandular types.

Non-glandular trichomes

• Unicellular: These are one-celled hairs. Some examples include:
  • Papillae (simple, short, conical hairs).
  • Cystolith hairs (contain calcium carbonate).
  • Warty hairs (with a warty cuticle)
• Multicellular: These are multiple-celled structures, further classified as unbranched or branched hairs. Some examples include:
  • Uniseriate (single row).
  • Biseriate (two rows).
  • Pluriseriate (multiple rows).
  • Simple branched (with two branches).
  • Stellate (star-shaped).
  • Peltate (having a flattened base).
  • Candelabra hairs (having multiple branches from a central axis).

Glandular Trichomes

• These possess glands on their head(s) distinguishing them from non-glandular.
• Unicellular or multicellular glands may be present.

Other structures

• Unicellular or Multicellular stalks may accompany the head structures in glandular hairs. Some examples include:
  • Uniseriate stalks
  • Biseriate stalks
  • Pluriseriate stalks
  • Branched stalks

This quiz explores the intricacies of leaf anatomy and the various components of plant cells. Delve into topics such as cytology, the unique features of plant cells, and the classification of plant tissues. Test your knowledge on the microscopic structures that play crucial roles in plant physiology.