Plant Structure

Plant Form

1. What is a plant? 2. Meristems elaborate the plant body 3. Major Plant Organs: Morphology and anatomy Roots Stems Leaves 4. Tissues found in plants Ground Vascular Dermal

Plant Organs Leaf Anatomy Shoot

Root

Stem Anatomy

Root Anatomy

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Cell Wall

Apical Meristems 1. Shoot apical meristem forms 1o meristems – Protoderm – Procambium – Ground meristem

2. Root apical meristem forms 1o meristems – Protoderm – Procambium – Ground meristem

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Shoot Meristems Fig. Secondary 35.05a(TE Art)

Primary & Secondary Meristems 1. Primary Meristems – Protoderm, protocambium & ground meristem – Responsible for elongation growth – Types

Ground meristem

Apical meristem Protoderm Procambium

• Shoot primary meristem • Root primary meristem

2. Secondary Meristem = Lateral meristem – Responsible for diameter growth – Types

Vascular cambium Cork cambium

Lateral meristems

• Vascular cambium • Cork cambium

Shoot Secondary Growth

Shoot Secondary Growth

Cork Cambium

Vascular Cambium Annual Ring

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Root Secondary Growth

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Primary Meristems Produce Tissue Systems

1 1 Apical Meristem

Primary Meristems

2 2

Protoderm Æ Dermal Tissue System Epidermis Trichomes Stomatal Complexes Ground Meristem Æ Ground Tissue System Cortex Pith

3 ProcambiumÆ Vascular Tissue System Xylem Phloem

1. Vascular cambium & 2o phloem 2. Secondary xylem 3. Periderm 4. Cork and cork cambium

Parenchyma

Ground (Fundamental) Tissue System • Characteristics – – – –

• Components – Parenchyma – Collenchyma – Sclerenchyma

Living cells Thin, primary cell wall Large vacuoles and thin band of cytoplasm Store starch, oils, tannins crystals

• Where is it found? – Cortex of stems and roots – Pith of stems – Mesophyll of leaves

• Special types of parenchyma – Chlorenchyma – Aerenchyma

Parenchyma

Parenchyma • Special types and functions of parenchyma – Synthetic - mesophyll – Meristematic – apical meristems – Secretory – glands and nectaries – Structural - aerenchyma – Boundary - epidermis & endodermis – Transport - transfer cells

Aerenchyma in papyrus

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Leaf & Root Parenchyma

Specialized Parenchyma

Palisade mesophyll (parenchyma)

Spongy mesophyll (parenchyma)

Root cortex (parenchyma)

Collenchyma

• • • •

Aerenchyma in papyrus

Collenchyma

Living cytoplasm Unevenly thickened primary cell walls Usually just beneath the epidermis Function: flexible support

Sclerenchyma

Sclerenchyma Sclereids

• Characteristics of sclerenchyma – Cells dead at maturity – Thick secondary cell walls – Lignified cell walls

• Types of sclerenchyma – Sclereids or stone cells - isodiametric – Fibers – very long sclerenchyma cells Economic value: Ropes, string canvas

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Sclerenchyma: Fibers

Vascular Tissue 1. Xylem 2. Phloem

Xylem: Tracheids,Vessel Members & Perforation Plates

Xylem: Tracheids and Vessel Members Vessel - Perforation plates

Simple

Reticulate Scalariform

Tracheid – Imperforate cell = No perforation plate

Tracheids

Xylem Secondary Wall Architecture 1

Vessel Members

Xylem: Bordered Pits

Bordered Pit

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Xylem: Transverse section

Xylem: Longitudinal section

Types of Secondary Wall Thickenings in Xylem 1. Annular 2. Helical 3. Scalariform 4. Reticulate 5. Pitted

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Vascular Tissue

Phloem

Xylem Phloem Fibers

Phloem Cell Characteristics

Phloem Anatomy • Sieve elements – Sieve cells – Sieve tube members • form sieve tubes

• Companion cells • Phloem parenchyma

Pores

Phloem Parenchyma

Dermal Tissue System Types of epidermal cells

Dermal Tissue System - Ordinary Epidermal Cells Morphology: Wavy, elongated, tabular ≈ flattened

1. Ordinary epidermal cells 2. Stomatal Complexes 3. Trichomes Epidermis of Galium aparine leaf Epidermis of Zygochloa leaf (a grass)

Tradescantia upper epidermis

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Dermal Tissue System Epidermal Cell Characteristics

Stomatal Complexes

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2 1 Epidermis of Tulipa leaf

Oleander upper epidermis Guard cell expressing green fluorescent protein bound to talin, a protein that binds to actin filaments. Red/orange structures are chloroplasts.

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3 4. Aglaophyton guard cells

Trichomes

Trichomes

Mullein Leaf SEM

Dermal Tissue System Stomatal Apparatus

Cuticle

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