BOTANY LEC MODULE 4 HISTOLOGY

HISTOLOGY

STUDY OF TISSUES

HISTOS

TISSUE

LOGIA

STUDY OF

CELLS WITH SIMILAR STRUCTURES TEND TO GROUP THEMSELVES AND FORM TISSUES

HOW ARE TISSUES FOMED?

TISSUE SYSTEM

FUNCTIONAL UNIT THAT CONNECTS ALL ORGANS OF A PLANT

CELL —> TISSUE —> TISSUE SYSTEM

PROCESS OF FORMATION OF TISSUES

PLANT TISSUE

group of closely associated cells - cells with same functions

CLASSIFICATIONS OF PLANT TISSUES

• DERMAL

• GROUND

• VASCULAR

MERISTEMATIC

SITE OF CELL DIVISION

PERMANENT

MATURE CELLS - NO CELL DIVISION

CLASSIFICATIONS OF PERMANENT CELLS

• SIMPLE

• COMPLEX

SIMPLE

CONTAINS 1 TYPE OF CELL

COMPLEX

ONE OR MORE TYPE OF CELLS

4 COMPONENTS OF SIMPLE

• EPIDERMIS

• PARENCHYMA

• COLLENCHYMA

• SCLERENCHYMA

2 COMPONENTS OF COMPLEX

• PHLOEM - TRANSPORT OF FOOD AND MINERALS

• XYLEM - TRANSPORT OF WATE

SHOOT SYSTEM

SHOOT

APICAL

MERISTEM

ROOT SYSTEM

ROOT

APICAL

SYSTEM

PRIMARY MERISTEM

• PROTODERM

• GROUND MERISTEM

• PROCAMBIUM

PROTODERM

OUTERMOST + FORMS EPIDERMIS

GROUND MERISTEM

GROUND TISSUE (CORTEX & PITH)

PROCAMBIUM

INNERMOST + PRIMARY VASCULAR TISSUE

MERISTEMS

WHERE TISSUES ORIGINATE

PARTS OF MERISTEMS

• APICAL MERISTEM

• LATERAL MERISTEM

• INTERCALARY MERISTEM

APICAL MERISTEM

• LENGTHENS STEMS AND ROOTS

• PRIMARY GROWTH

LATERAL MERISTEM

• INCREASE WIDTH OF STEMS

• SECONDARY GROWTH

2 TYPES OF LATERAL MERISTEM

• VASCULAR CAMBIUM

• CORK CAMBIUM

VASCULAR CAMBIUM

• CAMBIUM

• PRODUCES SECONDARY TISSUES

• SUPPORT AND CONDUCTION

• THIN CYLINDER; BRICK-SHAPED CELLS

• INITIALS - INDIVIDUAL REMAINING CELLS

• DERIVATIVES - SISTER CELLS

CORK CAMBIUM

• THIN CYLINDER THAT RUNS THE LENGTH OF STEMS AND ROOTS OF WOODY PLANTS

• PRODUCES CORK CELLS

• OUTSIDE VASCULAR CAMBIUM

INTERCALARY MERISTEMS

• FOUND IN VICINITY NEAR NODES (LEAF ATTACHMENT AREAS)

• HAVE NEITHER VASCULAR/CORK CAMBIUM

• THEIR TISSUES ADD TOO STEM LENGTH

3 REGIONS OF LEAVES

• EPIDERMIS

• MESOPHYLL

• VEINS

TISSUES PRODUCED BY MERISTEMS

• DERMAL

• GROUND

• VASCULAR

DERMAL TISSUE

• PROTECTS PLANT FROM INJURY & WATER LOSS

• CONTROLS INTERACTIONS WITH THE PLANTS’ SURROUNDINGS

• WATERPROOFING

DERMAL TISSUES

• EPIDERMIS

• PERIDERM

• MESOPHYLL

EPIDERMIS

• SINGLE LAYER OF CELLS

• EXIST IN YOUNGER PLANTS

• SECRETES FATTY SUBSTANCE - CUTIN

• SECRETES WAXY MATERIAL THAT INHIBITS WATER LOSS - CUTICLE

• GUARD CELL & STOMATA - gas exchange

• produces aerial roots - VELAMEN ROOTS

CUTIN

Fatty substance in epidermis

CUTICLE

waxy material produced by cutin

STOMATA

gas exchange in epidermis

VELAMEN ROOTS

aerial roots (orchids)

PERIDERM

• outermost part of woody plants

• box-like cork cells (dies at maturity)

• CORK CELLS —> SUBERIN (waxy fatty substance)

• LENTICEL - gas exchange

SUBERIN

waxy fatty substance in periderm

LENTICEL

gas exchange in periderm

BULLIFORM CELLS

BUBBLE-SHAPED CELL

ONLY IN MONOCOTS

MESOPHYLL

• where most photosynthesis takes place

• PALISADE MESOPHYLL

• SPONGY MESOPHYLL

2 TYPES OF MESOPHYLL

PALISADE MESOPHYLL

• 80% of leaves contain chloroplast

• upper region

• compactly stacked barrel-shaped parenchyma cells in 2 rows

SPONGY MESOPHYLL

• lower region

• loosely arranged parenchyma cells

• numerous chloroplast

• air spaces - prevent water loss

• NOT IN MONOCOTS

GROUND TISSUE

• Photosynthesis

• storage

• regeneration

• support

• protection

• PARENCHYMA

• COLLENCHYMA

• SCLERENCHYMA

3 TYPES OF GROUND TISSUES

PARENCHYMA

• thin cell walls & large vacuoles

• most abundant of all cells

• intercellular space is found

• FUNCTION: PHOTOSYNTHESIS & STORE PROTEIN AND STARCH (AMYLOPLAST)

AERENCHYMA

aquatic plants

CHLORENCHYMA

contains chloroplaSt

COLLENCHYMA

• elongated cells & thick cell walls

• no intercellular space

• support for growing tissues

• irregularly shaped

• PECTIN & CELLULOSE

SCLERENCHYMA

• narrow dead thick-walled cells

• provide support for plant

• LIGNIN - hardening agent

• LUMEN - tiny cavity

• 2 forms: SCHELEREIDS & FIBERS

LIGNIN

hardening agent of sclerenchyma

LUMEN

tiny cavity

• SCLEREIDS

• FIBERS

2 FORMS OF SCLERENCHYMA

VASCULAR TISSUE

transports material between the root and the shoot of the plant

• XYLEM

• PHLOEM

XYLEM

• combination of parenchyma cells, fibers, vessel, tracheid, ray cells

• transport of water

• upward movement

• dead & hollow at maturity

• VESSELS & TRACHEID

PHLOEM

• transport of food and minerals

• SIEVE TUBE MEMBERS - main conducting cells

• COMPANION CELLS - assist in loading sugars

• CIRCULATORY SYSTEM OF PLANTS

SIEVE TUBE MEMBERS

main conducting cells of phloem

COMPANION CELLS

assist in loading sugars assist in loading sugars in phloem

VESSELS

long tubes; composed of vessel elements

TRACHEIDS

dead at maturity; thick secondary walls

FLOWERING PLANTS

MONOCOT

DICOT

• WOODY DICOTS

• HERBACEOUS DICOTS

• MONOCOTS

3 BASIC TISSUE PATTERN

CHLOROPLAST

CELL WALL

CENTRAL VACUOLE

ORGANELLES FOUND IN PLANT CELLS THAT ANIMAL CELLS DO NOT HAVE