Plant Anatomy Overview

• Key Components of Plant Anatomy

  • Light (Photosynthesis)

  • CO2 (Carbon Dioxide)

  • H2O (Water)

  • Plant Structures: Leaf, Stem, Root

General Structure

• Plant Organization

  • Above Ground Components

  • Below Ground Components

  • Reproductive/Flowering Parts

Reproductive Structures

• Reproductive Shoot Components

  • Apical Bud: Growing tip of the shoot

  • Node: Point where leaves attach

  • Internode: Space between nodes

• Other Structures

  • Shoot System: Comprised of vegetative and reproductive shoots

  • Blade: Flattened part of the leaf

  • Petiole: Stalk connecting leaf blade to the stem

  • Axillary Bud: Potential stem that can form a new shoot

  • Stem: Supports structure, carries nutrients and water

• Root Systems

  • Taproot: Main root growing downward

  • Lateral Roots: Branches off the taproot

Leaf Anatomy

• General Features of Leaves

  • Epidermis: Protective outer layer

  • Stomata: Pores for gas exchange

  • Palisade Cells: Photosynthesis cells containing chlorophyll

• Leaf Shape Characteristics

  • Outline: Overall shape of the leaf

  • Margin: Edges of the leaf

  • Base: Leaf attachment point

  • Tip: Apex of the leaf

  • Venation: Pattern of veins within the leaf

Leaf Outline Types

• Various Leaf Shapes

  • Cordate: Heart-shaped

  • Deltoid: Triangular

  • Linear: Long and narrow

  • Oblanceolate: Wider at the tip

  • Ovate: Egg-shaped

  • Spathulate: Spoon-shaped

  • Reniform: Kidney-shaped

  • Peltate: Shield-shaped

Leaf Margin Types

• Leaf Margin Variations

  • Entire: Smooth edge

  • Serrate: Saw-toothed edge

  • Incised: Deeply cut edges

  • Lacerate: Irregular edge

  • Lobed: Divided margin

Leaf Base and Tip Shapes

Leaf Base Shapes

• Acuminate, Rounded, Auriculate, Sagittate, Cordate, Oblique, Hastate, Truncate

Leaf Tip Shapes

• Acuminate, Acute, Emarginate, Cuspidate, Aristate, Mucronate, Obtuse, Rounded, Truncate

Leaf Types

• Simple Leaf: Single undivided blade

  • Pinnate leaflets: Individual leaflets on a petiole

• Compound Leaf: Multiple leaflets on a single petiole

• Doubly Compound Leaf: Leaflets that are further divided into smaller leaflets

Leaf Venation and Arrangement

• Leaf Venation Types

  • Dichotomous: Forking pattern

  • Parallel: Straight parallel veins

  • Palmately Veined: Spread from a single point

  • Pinnately Veined: Central vein with side branches

• Leaf Arrangement Types

  • Alternate: One leaf per node

  • Opposite: Two leaves per node

  • Whorled: Three or more leaves per node

  • Rosette: Leaves arranged in a rosette pattern close to the ground

Trichomes and Stomata

• Types of Trichomes

  • Simple (unicellular/multicellular), Complex

  • Urtica diocia (Nettle): Examples of stinging trichomes

• Stomata: Main points for gas exchange on lower leaf surface

Leaf Microstructure

• Leaf Layers

  • Cuticle: Waxy outer layer to reduce water loss

  • Upper Epidermis: Protective layer with fewer stomata

  • Palisade Mesophyll: Main photosynthetic layer

  • Spongy Mesophyll: Air spaces for gas exchange

  • Lower Epidermis: Contains stomata and guard cells

Modified Leaves

• Storage Leaves: Specialized for storing water in succulents, e.g., Deleospermum sp.

• Spines: In cacti, leaves reduced to spines; stem performs photosynthesis

• Tendrils: Climbing structures in pea plants, modified leaves for support

• Bracts: Modified leaves that may mimic petals, attract pollinators

Shoot Anatomy

• Shoot Structure

  • Terminal Bud: Main growing point

  • Node and Internode: Structure and growth areas

  • Lenticel: Pores in the stem allowing gas exchange

  • Leaf Scar: Mark left by fallen leaves

Root Anatomy

• Root Cap: Protective tip of the root

• Epidermis, Cortex, and Stele: Key root structures for nutrient and water uptake

• Root Tip Meristem: Growth region for root development

Modified Shoots and Roots

• Rhizomes: Horizontal underground shoots

• Bulbs: Enlarged underground stems for food storage

• Stolons: Above-ground runners for propagation in strawberries

• Tubers: Storage roots (e.g., potatoes) with axillary buds

• Corms: Swollen stem bases for storage with protective tunics

Monocots vs. Dicots

Monocots

• One cotyledon, scattered vascular bundles, parallel leaf veins, flower parts in multiples of three

Dicots

• Two cotyledons, vascular bundles in a ring, net-like leaf veins, flower parts in multiples of four or five

Flower Anatomy and Morphology

• Key Flower Parts

  • Sepal, Petal, Stamen (male), Carpel (female), Filament, Ovary

• Gynoecium Composition: Apocarpous (separate carpels) vs. Syncarpous (fused carpels)

• Ovary Position Types: Hypogynous, Perigynous, Epigynous

Inflorescence Types

• Arrangement of Flowers on a Plant

  • Peduncle: Main stalk of the inflorescence

  • Types: Solitary, Spike, Umbel, Compound Umbel

Plant Cell Structure

• Important Organelles

  • Cell Wall: Rigid support structure only in plants

  • Chloroplasts: Site of photosynthesis

  • Mitochondria: Energy production

  • Vacuoles: Storage and maintenance of turgor pressure

  • Golgi Apparatus: Processes and packages macromolecules

Conclusion

• Understanding plant anatomy and physiology is crucial for fields such as botany, agriculture, horticulture, and ecology.