Plant Structures

Plant Structures

Roots, Stems, and Leaves

Roots, Stems, and Leaves

Chapter 23

Chapter 23

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Plants are as

Plants are as

successful if not

successful if not

more successful than

more successful than

animals

animals



Seed plants have

Seed plants have

three main

three main

structures:

structures:



Roots

Roots



Stems

Stems



Leaves

Leaves



Linked together by

Linked together by

various means

various means

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Roots

Roots



Absorbs water and

Absorbs water and

nutrients

nutrients



Anchor plant to the

Anchor plant to the

ground

ground



Hold soil in place and

Hold soil in place and

prevent erosion

prevent erosion



Protect from soil

Protect from soil

bacteria

bacteria



Transport water and

Transport water and

nutrients

nutrients



Provide upright

Provide upright

support

support

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Stems

Stems



Support for the

Support for the

plant body

plant body



Carries nutrients

Carries nutrients

throughout plant

throughout plant



Defense system to

Defense system to

protect against

protect against

predators and

predators and

infection

infection



Few millimeters to

Few millimeters to

100 meters

100 meters

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Leaves

Leaves



Main

Main

photosynthetic

photosynthetic

systems

systems



Suseptable to

Suseptable to

extreme drying

extreme drying



Sight of

Sight of

oxygen/carbon

oxygen/carbon

dioxide intake and

dioxide intake and

release

release

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Plant tissue

Plant tissue

systems

systems



Exist within the

Exist within the

root, stems,

root, stems,

and leaves

and leaves



Dermal tissue

Dermal tissue



Vascular tissue

Vascular tissue



Ground tissue

Ground tissue

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Dermal Tissue

Dermal Tissue



Outer covering

Outer covering



Single layer of cells

Single layer of cells



Cuticle

Cuticle

– waxy

– waxy

coating

coating



Trichomes

Trichomes

–

–

Spiny

Spiny

projections on the leaf

projections on the leaf



Roots have dermal

Roots have dermal

tissue

tissue



Root hairs

Root hairs



Guard Cells

Guard Cells

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Vascular Tissue

Vascular Tissue



Transport System

Transport System



Subsystems

Subsystems



Xylem

Xylem



Phloem

Phloem



Subsystems are used to carry

Subsystems are used to carry

fluids throughout plant

fluids throughout plant

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Xylem

Xylem



Two types

Two types



Seed plants

Seed plants



Angiosperms

Angiosperms



Tracheid

Tracheid

– long

– long

narrow cells

narrow cells



Walls are connected

Walls are connected

to neighboring cells

to neighboring cells



Will eventually die

Will eventually die



Vessel Element

Vessel Element

–

–

wider that trachieds

wider that trachieds

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Phloem

Phloem



Sieve Tube Elements

Sieve Tube Elements



Cells arranged end to end

Cells arranged end to end



Pump sugars and other foods

Pump sugars and other foods



Companion Cells

Companion Cells



Surround sieve tube elements

Surround sieve tube elements



Support phloem cells

Support phloem cells

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Ground Tissue

Ground Tissue



Cells between dermal

Cells between dermal

and vascular tissue

and vascular tissue



Parenchyma

Parenchyma



Thin cell walls, large

Thin cell walls, large

vacuoules

vacuoules



Collenchyma

Collenchyma



Strong, flexible cell

Strong, flexible cell

walls

walls



Sclerenchyma

Sclerenchyma



Extremely thick, rigid

Extremely thick, rigid

cell walls

cell walls

23-1 Specialized Tissues

23-1 Specialized Tissues

in Plants

in Plants



Plant Growth

Plant Growth



Meristems

Meristems

– tissues

– tissues

responsible for growth

responsible for growth



Undifferentiated cells

Undifferentiated cells



Apical Meristem

Apical Meristem



Produce growth

Produce growth

increased length

increased length



Differentiation

Differentiation



Cells will assume roles

Cells will assume roles

in the plant

in the plant



Flower Development

Flower Development



Starts in the meristem

Starts in the meristem

23-2 Roots

23-2 Roots



Types of Roots

Types of Roots



Taproots

Taproots



Found in dicots

Found in dicots



Long, thick root

Long, thick root



Hickory and oak trees

Hickory and oak trees



Fibrous roots

Fibrous roots



Found in monocots

Found in monocots



No single root larger than any other

No single root larger than any other



Many thin roots

Many thin roots

23-2 Roots

23-2 Roots



Root Structure

Root Structure



Outside layer

Outside layer



Epidermis

Epidermis



Root hairs

Root hairs



Cortex

Cortex



Central cylinder –

Central cylinder –

vascular system

vascular system



Root Cap – cellular

Root Cap – cellular

production

production



Key role in

Key role in

water/mineral

water/mineral

transport

transport

23-2 Roots

23-2 Roots



Root Functions

Root Functions



Anchor plant

Anchor plant



Absorb water

Absorb water



Absorb nutrients

Absorb nutrients

23-2 Roots

23-2 Roots



Plant Nutrient

Plant Nutrient

Uptake

Uptake



Soil type determines

Soil type determines

plant type

plant type



Plant requirements

Plant requirements



Oxygen, CO

Oxygen, CO

2

2



Nitrogen

Nitrogen



Phosphorus

Phosphorus



Postassium

Postassium



Magnesium

Magnesium



Calcium

Calcium



Trace elements

Trace elements

23-2 Roots

23-2 Roots



Active Transport in

Active Transport in

Plants

Plants



Root hairs use ATP

Root hairs use ATP



Pump minerals from

Pump minerals from

soil

soil



Causes water

Causes water

molecules to follow by

molecules to follow by

osmosis

osmosis



Vascular Cylinder

Vascular Cylinder



Casparian Strip –

Casparian Strip –

water retention

water retention



Root Pressure

Root Pressure



Forces water up into

Forces water up into

the plant

the plant

23-3 Stems

23-3 Stems



Stem Structure

Stem Structure



Produce leaves,

Produce leaves,

branches, and flowers

branches, and flowers



Hold leaves up

Hold leaves up



Transport substance

Transport substance

between roots and

between roots and

leaves

leaves



Essential part of

Essential part of

transport system

transport system



Function in storage

Function in storage

and photosynthesis

and photosynthesis

23-3 Stems

23-3 Stems



Xylem and phloem –

Xylem and phloem –

major tubule systems

major tubule systems



Transport water and

Transport water and

nutrients

nutrients



Composed of three

Composed of three

tissue layers

tissue layers



Contain

Contain

nodes

nodes

–

–

attachment for leaves

attachment for leaves



Internodes

Internodes

– regions

– regions

between the nodes

between the nodes



Buds

Buds

– undeveloped

– undeveloped

tissue

tissue

23-3 Stems

23-3 Stems



Stem Types

Stem Types



Monocot

Monocot

–

–

vascular bundles

vascular bundles

are scattered

are scattered

throughout

throughout



Distinct epidermis

Distinct epidermis



Dicot

Dicot

– vascular

– vascular

tissue arranged in a

tissue arranged in a

cylinder

cylinder



Pith

Pith

– parenchyma

– parenchyma

cells inside the ring

cells inside the ring

23-3 Stems

23-3 Stems



Stem Growth

Stem Growth



Primary growth – new

Primary growth – new

cells produced at the

cells produced at the

root tips and shoots

root tips and shoots



Increases the length

Increases the length



Secondary growth –

Secondary growth –

increase in stem width

increase in stem width



Vascular cambium –

Vascular cambium –

produces tissue and

produces tissue and

increases thickness

increases thickness



Cork cambium –

Cork cambium –

produces outer

produces outer

covering of stems

covering of stems

23-3 Stems

23-3 Stems



Formation of

Formation of

Vascular Cambium

Vascular Cambium



Xylem and phloem

Xylem and phloem

bundles present

bundles present

intially

intially



Secondary growth

Secondary growth

initiates production

initiates production

of a thin layer

of a thin layer



The vascular

The vascular

cambium divides

cambium divides



Produces new xylem

Produces new xylem

and phloem

and phloem

23-3 Stems

23-3 Stems



Formation of wood

Formation of wood



Wood – layers of exlem

Wood – layers of exlem



Produced year after year

Produced year after year



Results from the older xylem not conducting water –

Results from the older xylem not conducting water –

heartwood

heartwood



Becomes darker with age

Becomes darker with age



Sapwood

Sapwood

– surrounds heartwood

– surrounds heartwood

23-3 Roots

23-3 Roots



Formation of Bark

Formation of Bark



All the tissues

All the tissues

outside the

outside the

vascular cambium

vascular cambium



Consists of

Consists of

outermost layers of

outermost layers of

dead cork

dead cork



Water proof

Water proof

23-4 Leaves

23-4 Leaves



Main sight of

Main sight of

photosynthesis

photosynthesis



Consist of:

Consist of:



Blade – thin flattened

Blade – thin flattened

section

section



Petiole – stalk that

Petiole – stalk that

attaches stem to blade

attaches stem to blade



Covered by

Covered by

epidermis and cuticle

epidermis and cuticle



Create water proof

Create water proof

barrier

barrier

23-4 Leaves

23-4 Leaves



Leaf Functions

Leaf Functions



Photosynthesis –

Photosynthesis –

occurs in the

occurs in the

mesophyll

mesophyll



Palisade mesophyll –

Palisade mesophyll –

absorb light

absorb light



Spongy mesophyll –

Spongy mesophyll –

beneath palisede level

beneath palisede level



Stomata – pores in the

Stomata – pores in the

underside of the leaf

underside of the leaf



Guard Cells

Guard Cells

–

–

Surround the stomata

Surround the stomata

23-4 Leaves

23-4 Leaves



Transpiration

Transpiration



Loss of water through its leaves

Loss of water through its leaves



Replaced by water drawn into the leaf

Replaced by water drawn into the leaf

23-4 Leaves

23-4 Leaves



Gas Exchange

Gas Exchange



Take in CO

Take in CO

2

2

and

and

release O

release O

2

2



Can also do the

Can also do the

opposite – How?

opposite – How?



Gas exchange takes

Gas exchange takes

place at the stomata

place at the stomata



Not open all the time

Not open all the time



Stomata is controlled

Stomata is controlled

by water pressure in

by water pressure in

guard cells

guard cells

23-5 Transport in Plants

23-5 Transport in Plants



Water Transport

Water Transport



Active transport

Active transport

and root pressure

and root pressure



Cause water to

Cause water to

move from soil to

move from soil to

roots

roots



Capillary action

Capillary action



Combined with

Combined with

active transport and

active transport and

root pressure,

root pressure,

moves materials

moves materials

throughout the plant

throughout the plant

23-5 Transport in Plants

23-5 Transport in Plants



Capillary Transport

Capillary Transport



Capillary transport

Capillary transport

results from both

results from both

cohesive and

cohesive and

adhesive forces

adhesive forces



Water molecules

Water molecules

attracted to one

attracted to one

another

another



Water is also

Water is also

attracted to the xylem

attracted to the xylem

tubes in the plant

tubes in the plant



Causes water to move

Causes water to move

from roots to the

from roots to the

stem and upward

stem and upward

23-5 Transport in Plants

23-5 Transport in Plants



Transpiration

Transpiration



Evaporation is the

Evaporation is the

major moving force

major moving force



As water is lost,

As water is lost,

osmotic pressure

osmotic pressure

moves water out of

moves water out of

vascular tissue

vascular tissue



This pulls water up

This pulls water up

from the stem to the

from the stem to the

leaves

leaves



Affected by heat,

Affected by heat,

humidity, and wind

humidity, and wind

23-5 Transport in Plants

23-5 Transport in Plants



Controlling

Controlling

Transpiration

Transpiration



Open the stomata –

Open the stomata –

increase water loss

increase water loss



Close the stomata –

Close the stomata –

decrease water loss

decrease water loss

23-5 Transport in Plants

23-5 Transport in Plants



Transpiration and

Transpiration and

Wilting

Wilting



Osmotic pressure –

Osmotic pressure –

keeps plants semi-rigid

keeps plants semi-rigid



Wilting is a result of

Wilting is a result of

high transpiration

high transpiration

rates

rates



Loss of water causes a

Loss of water causes a

drop in osmotic

drop in osmotic

pressure

pressure



Loss of rigidity

Loss of rigidity



Conserves water

Conserves water

23-5 Transport in Plants

23-5 Transport in Plants



Nutrient Transport

Nutrient Transport



Most nutrients are

Most nutrients are

pushed

pushed

through plant

through plant



Nutrient movement

Nutrient movement

takes place in phloem

takes place in phloem



Source to Sink

Source to Sink



Source – any cell that

Source – any cell that

produces sugars

produces sugars



Sink – any cell where

Sink – any cell where

sugars are used

sugars are used



Pressure-flow

Pressure-flow

Hypothesis

Hypothesis