Plant Anatomy and Physiology Quiz

Crude Drugs Localized in Leaves

• Active constituents in crude drugs are often found concentrated in leaves.
• Pharmacognostical studies of these drugs include botanical studies to identify the drug in its whole form and powdered form.
• These studies also cover the main active constituents, their uses, and potential side effects.

Plant Parts

• Shoot system: Consists of the stem and its associated parts, crucial in food production (photosynthesis).
  • Leaves: Primary site of photosynthesis, vital for food production.
  • Flowers: Responsible for reproduction. Fertilization transforms flowers into fruit that contains seeds.
  • Apical bud: Responsible for stem elongation.
  • Axillary bud: Forms lateral branches and flowers.
• Root system: Responsible for absorbing water and nutrients essential for plant life and photosynthesis.
  • Primary root: The main root.
  • Lateral roots: Branching roots extending from the primary root.

Leaf Structure

• Leaves are lateral outgrowths on the stem, lacking nodes and internodes.
• They have lateral branches arising from their axils.
• Leaves consist of three main parts:
  • Leaf lamina (blade): The green, wide part.
  • Leaf petiole: Connects the leaf to the stem.
  • Leaf base: The point of attachment to the stem.
• Leaf margin and apex: Defining features of the leaf shape.
• Vennation (veins): The leaf veins show different patterns.
• Stipules: Lateral projections at the leaf base that protect the axillary bud. They can be hairy, leafy, or spiny. (Present or absent).

Leaf Functions

• Photosynthesis: The leaf is the primary site for converting light energy into chemical energy (food).
• Food material formation: Photosynthesis produces food, storing energy for the plant.
• Gas exchange: Leaves facilitate gas exchange between the atmosphere and the plant's tissues, crucial for photosynthesis and respiration. This exchange happens through stomata.

Leaf Types

• Foliage leaves: Primarily involved in photosynthesis.
• Floral leaves: Modified leaves that form part of a flower.
• Modified leaves: Leaves adapted for specific functions like defense (spines) or support (tendrils).

Types of Leaves (Continued)

• Cotyledons: Seed leaves, providing initial nutrients.
• Prophylls: First leaves on a stem or shoot.
• Bracts: Modified leaves associated with flowers or inflorescences.
• Scaly leaves: Small, protective leaves.

Leaf Insertion

• Cauline leaves: Attached directly to the stem.
• Radical leaves: Arranged on a root-like structure.

Leaf Arrangement (Phyllotaxis)

• Alternate/spiral: One leaf per node.
• Opposite: Two leaves per node, opposite each other.
• Whorled: Three or more leaves per node.

Leaf Base or Phyllopodium

• Stipules: Lateral projections at the leaf base.
• Sheath: Part of the leaf base that surrounds the stem.

Leaf Petiole

• Petiolate: Leaves with a petiole (stalk).
• Sessile: Leaves without a petiole; attached directly to the stem.

Leaf Lamina (Blade)

• Simple: Undivided leaf blade.
• Compound: Leaf blade divided into leaflets.
  • Lobed: Has lobes.
• Types of simple leaves:
• Filiform
• Acicular
• Tubular
• Linear
• Oblong
  • Types of compound leaves:
• Binate
• Ternate
• Palmate
• Pinnate -Types of Pinnate leaves:
• Parapinnate
• Imparipinnate

Leaf Shape (Lamina)

• Shape categories based on widest portion near the base:
• Lanceolate, Ovate, Ensiform, Haustate, Cordate, Sagittate, Reniform
• Shape categories based on widest portion near the apex:
  • Lyrate, Obcordate, Obovate, Spathulate
• Symmetric/Rounded categories:
  • Oval, Elliptical, Peltate, Orbicular

Leaf Margin

• Entire (smooth): No incisions in the margin.
• Serrate: Tooth-like incisions, pointed outwards.
• Crenate: Tooth-like incisions, rounded/rounded outward.
• Dentate: Tooth-like incisions, sharp.
• Ciliate: Hair-like structures along the margin.

Leaf Base (Lamina)

• Symmetric: Equal sides.
• Asymmetric: Unequal sides.
• Decurrent: Leaf base extends down and adjoins the stem.

Leaf Venation

• Types of leaf venation:
• Pinnate
• Palmate
• Parallel

Leaf Surface

• Leaf surface features:
  • Color (upper surface is often darker)
  • Midrib prominence (more prominent on underside)
  • Textures: гладкий, rugose (wrinkled), punctate (dotted, often from glands), scabrous (rough), glabrous (smooth, free of hairs), pubescent (hairy), succulent (thick and fleshy).

Leaf Texture

• Membranous: Very thin and pliable.
• Papery: Thin, like paper.
• Coriaceous: Thick and leathery.
• Succulent: Thick and fleshy.

Leaf Micromorphology (Anatomy)

• To identify plant powders, one needs to know the basic anatomy.

Plant Cell Wall

• Middle lamella: Pectin layer binding cells together.
• Primary cell wall: Cellulose only.
• Secondary cell wall: Cellulose, hemicellulose, or lignin, adding strength.

Plant Tissue Composition

• Epidermis: Outermost layer, protecting the plant.
• Vascular tissue: Transports water and minerals (xylem) and food (phloem).
• Ground tissue: Cells in between; versatile functions (Parenchyma, Collenchyma, Sclerenchyma).

Ground Cells: Parenchyma

• Thin-walled cells, often with large intercellular spaces.
  • Chlorenchyma: Contains chlorophyll, involved in photosynthesis.
  • Aerenchyma: Contains air spaces, involved in gas exchange.
  • Storage parenchyma: Contains starch or other storage materials.

Ground Cells: Collenchyma

• Similar to Parenchyma, but cell walls are thicker, providing structural support.
• Types: angular, lamellar, lacunar.

Ground Cells: Sclerenchyma

• Thick-walled, dead cells providing rigid support.
  • Fiber cells: Elongated, running longitudinally through tissues.
  • Sclereids: Compact cells, providing support.

Vascular Tissue: Xylem

• Transports water and minerals.
  • Xylem vessels: Continuous cells with perforated end walls.
  • Tracheids: Elongated cells with tapering ends, important in water transport.
  • Xylem fibers: Support cells within the xylem.

Vascular Tissue: Phloem

• Transport of food.
  • Sieve tubes: Long cells with porous end walls (sieve plates).
  • Companion cells: Living cells surrounding sieve tubes, regulating their function.
  • Phloem fibers: Support cells within the phloem.

Vascular Bundles

• Kinds of Vascular bundles: Collateral, Closed, Bi-collateral, and Concentric (Amphiphloic/Amphivasal) - open and closed; position in relation to xylem/phloem

Epidermis

• Single-layered tissue, forming the outer protective layer of organs.
  • Epidermal cells: Basic components.
  • Stomata: Regulated opening of gas exchange.
  • Hairs: Additional structural and functional components.

Stomata

• Specialized pores in the epidermis for gas exchange.
  • Guard cells: Regulate the opening and closing of stomata.
  • Subsidiary cells: Surrounding cells around stomata.
• Types of Stomata: Dumbbell-shaped (grasses) and Bean-shaped (dicots).

Test your knowledge on plant anatomy and physiology with questions about leaf structures, tissue functions, and plant parts. This quiz covers essential concepts that are foundational to understanding how plants function and adapt to their environments.