Chapter 24: pp. 433 - 454
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10th Edition
Sylvia S. Mader
Flowering Plants:
Structure and
Organization
BIOLOGY
(Top left): © David Newman/Visuals Unlimited; (Top right): © Dwight Kuhn; (Bottom left): © Runk-Schoenberger/Grant Heilman Photography; (Bottom center): © Ardea London Ltd.;
(Bottom right): Courtesy George Ellmore, Tufts University
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
1
Outline

Plant Organs
Roots
 Stems
 Leaves


Monocots vs.
Eudicots
 Epidermal Tissue
 Ground Tissue
 Vascular Tissue



Roots

Organization

Diversity
Stems

Organization

Diversity
Leaves

Organization

Diversity
2
Organs of Flowering Plants

Flowering plants, or angiosperms, are extremely diverse.





Share many common structural features.
Most flowering plants possess a root system and a shoot system

The root system simply consists of the roots,

The shoot system consists of the stem and leaves.
A typical plant features three vegetative organs

The roots,

The stems, and

The leaves
Vegetative organs are concerned with growth and nutrition
Flowers, seeds, and fruits are structures involved in reproduction.
3
Plant Organs

Roots


Generally, the root system is at least equivalent in size
and extent to the shoot system

Anchors plant in soil

Absorbs water and minerals

Produces hormones
Root hairs:

Projections from epidermal root hair cells

Greatly increase absorptive capacity of root
4
Organization of Plant Body
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
terminal bud
blade
leaf
vein
petiole
axillary bud
stem
node
internode
node
vascular tissues
shoot system
root system
branch
root
root hairs
primary
root
5
Vegetative Organs of Several Eudicots
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
blade
stem
roots
petiole
stems
lateral root
a. Root system, dandelion
b. Shoot system, bean seedling
(All): © Dwight Kuhn
c. Leaves, pumpkin seedling
6
Stems

Shoot system of a plant is composed of the
stem, branches, and leaves

Stem is the main axis of a plant that elongates
and produces leaves
Nodes occur where leaves are attached to the stem
 Internode is region between nodes


Stem also has vascular tissue that transports
water and minerals
7
Leaves

Leaves are the major part of the plant that
carries on photosynthesis

Foliage leaves are usually broad and thin
Blade - Wide portion of foliage leaf
 Petiole - Stalk attaches blade to stem
 Leaf Axil - Axillary bud originates

Tendrils - Leaves that attach to objects
 Bulbs - Leaves that store food

8
Monocot vs. Eudicot

Monocots (Single cotyledon)
Cotyledons act as transfer tissue
 Root vascular tissue occurs in ring
 Parallel leaf venation


Eudicots (Two cotyledons)
Cotyledons supply nutrients to seedlings
 Root phloem located between xylem arms
 Netted leaf venation

9
Flowering Plants: Monocots or Eudicots
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Root
Stem
Leaf
Vascular bundles
scattered in stem
Leaf veins form
a parallel pattern
Flower
Monocots
Seed
Root xylem and
phloem in a ring
Flower parts in threes
and multiples of three
Eudicots
One cotyledon in seed
Two cotyledons in seed
Root phloem between
arms of xylem
Vascular bundles
in a distinct ring
Leaf veins form
a net pattern
Flower parts in fours or
fives and their multiples
10
Plant Tissues

Epidermal Tissues

Contain closely packed epidermal cells

Covered with waxy cuticle

Roots contain root hairs

Lower leaf surface contain stomata

Woody plants covered by cork
11
Modifications of Epidermal Tissue
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
corn seedling
guard cell
chloroplasts
periderm
lenticel
cork cambium
cork
root hairs
epidermal
cell
enlongating root tip
a. Root hairs
stoma
nucleus
20 m
b. Stoma of leaf
c. Cork of older stem
a: © B. Runk/S. Schoenberger/Grant Heilman Photography; b: © J.R. Waaland/Biological Photo Service; c: © Kingsley Stern
12
Ground Tissue

Ground tissue forms bulk of a plant


Parenchyma cells:

Least specialized and are found in all organs of
plant

Can divide and give rise to more specialized cells
Collenchyma cells:

Have thicker primary walls

Form bundles underneath epidermis

Flexible support to immature regions of the plant
13
Ground Tissue Cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a. Parenchyma cells
50 mm
50 mm
50 mm
b. Collenchyma cells
c. Sclerenchyma cells
(All): © Biophoto Associates/Photo Researchers, Inc.
14
Ground Tissue

Sclerenchyma cells:
Have thick secondary walls impregnated with
lignin
 Most are nonliving
 Primary function is to support mature regions
of the plant

Fibers
 Sclereids

15
Vascular Tissue

Xylem transports water and minerals from
the roots to the leaves

Tracheids

Long, with tapered ends




Pits in end walls
Vascular rays
Fibers
Vessel Elements

Larger, with perforated plates in their end walls
16
Xylem Structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
vessel
element
tracheids
xylem
parenchyma
cell
vessel
element
tracheid
perforation
plate
pitted
walls
pits
50 mm
a. Xylem micrograph (left) and drawing (to side)
b. T wo types of vessels
c. Tracheids
a: © J. Robert Waaland/Biological Photo Service
17
Ground Tissue

Sclerenchyma cells:
Have thick secondary walls impregnated with
lignin
 Most are nonliving
 Primary function is to support mature regions
of the plant

Fibers
 Sclereids

18
Vascular Tissue

Phloem transports sucrose and other organic
compounds from the leaves to the roots

Sieve-tube members are conducting cells

Contain cytoplasm but no nuclei

Channels in end walls

Plasmodesmata extend from one cell to another through
sieve plate
19
Phloem Structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
sieve plate
sieve-tube
member
sieve-tube member
companion cell
companion
cell
sieve plate
nucleus
phloem
parenchyma
cells
20 mm
a. Phloem micrograph (left) and drawing (to side)
b. Sieve-tube member and companion cells
a: © George Wilder/Visuals Unlimited
20
Organization of Roots

Root apical meristem

Located in the root tip

Protected by root cap

Primary meristems are in the zone of cell division

Zone of maturation contains fully differentiated
cells
21
Tissues of Eudicot Root
Epidermis
 Cortex
 Endodermis



Casparian Strip
Vascular Tissue

Pericycle
22
Eudicot Roots
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
endodermis
pericycle
phloem
xylem
cortex
epidermis
root hair
50 mm
b. Vascular cylinder
phloem
endodermis
Zone of
maturation
water and
minerals
Casparian
strip
xylem of
vascular
cylinder
Vascular
cylinder
pericycle
Zone of
elongation
c. Casparian strip
procambium
ground
meristem
Zone of
cell division
protoderm
root apical meristem
protected by
root cap
root cap
a. Root tip
a(Root tip): Courtesy Ray F. Evert/University of Wisconsin Madison; b: © CABISCO/Phototake
23
Branching of Eudicot Root
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
epidermis
emerging
branch root
cortex
pericycle
vascular
cylinder
endodermis
© Dwight Kuhn; 24.10a: © John D. Cunningham/Visuals Unlimited
24
Organization of Monocots Roots

Monocot roots:

Ground tissue of root’s pith is surrounded by
vascular ring

Have the same growth zones as eudicot roots,
but do not undergo secondary growth
25
Monocot Root
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
vascular
cylinder
a.
pith
phloem
xylem
pericycle
endodermis
cortex
epidermis
b.
100 mm
a: © John D. Cunningham/Visuals Unlimited; b: Courtesy George Ellmore, Tufts University
26
Root Diversity

Primary root (taproot) - Fleshy, long single root,
that grows straight down


Fibrous root system - Slender roots and lateral
branches


Stores food
Anchors plant to soil
Adventitous roots - Roots develop from organs of
the shoot system

Prop roots
27
Root Diversity

Haustoria:
Rootlike projections that grow into host plant
 Make contact with vascular tissue and extract
water and nutrients


Mycorrhizas:
Associations between roots and fungi
 Assist in water and mineral extraction


Root nodules - Contain nitrogen-fixing
bacteria
28
Root Diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.Taproot
b. Fibrous root system
c. Prop roots, a type of adventitious
root
d. Pneumatophores of black
mangrove trees
e. Aerial roots of English ivy clinging to tree trunks
a: © Dr. Robert Calentine/Visuals Unlimited; b: © Ed Degginger/Color Pic; c: © David Newman/Visuals Unlimited; d: © Terry Whittaker/Photo Researchers, Inc.;
e(Left): © Alan and Linda Detrick/Photo Researchers, Inc.; e(Right): © David Sieren/Visuals Unlimited
29
Organization of Stems

Shoot apical meristem
Produces new cells that elongate and increase
stem length
 Protected by terminal bud

Enveloped by leaf primordia
 Specialized primary meristems




Protoderm
Ground Meristem
Procambium
30
Woody Twig
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
bud scale
one year's
growth
lenticel
terminal bud
internode
node
node
terminal bud
scale scars
axillary bud
stem
leaf scar
bundle scars
31
Shoot Tip and Primary Meristems
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Three Primary Meristems:
protoderm
leaf primordium
shoot apical
meristem
protoderm
ground
meristem
procambium
ground
meristem
procambium
Primary Tissues
internode
epidermis
axillary bud
pith
cortex
vascular
cambium
vascular bundles
pith
primary xylem
vascular cambium
primary phloem
cortex
primary
xylem
primary
phloem
a. Shoot tip
b. Fate of primary meristems
32
Herbaceous Stems

Mature non-woody stems exhibit only
primary growth

Outermost tissue covered with waxy cuticle

Stems have distinctive vascular bundles

Herbaceous eudicots - Vascular bundles arranged
in distinct ring

Monocots - Vascular bundles scattered throughout
stem
33
Herbaceous Eudicot Stem
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
epidermis
cortex
pith
vascular
bundle
100 mm
phloem fiber
xylem
phloem
epidermis
pith
50 mm
vascular cambium parenchyma
collenchyma
(Top): © Ed Reschke; (Bottom): Courtesy Ray F. Evert/University of Wisconsin Madison
34
Monocot Stem
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
epidermis
ground tissue
vascular
bundle
ground tissue
(parenchyma)
xylem
phloem
vessel element
air space
bundle sheath cells
sieve-tube member
companion cell
(Top): © CABISCO/Phototake; (Bottom): © Kingsley Stern
35
Woody Stems

Woody plants have both primary and
secondary tissues

Primary tissues formed each year from primary
meristems

Secondary tissues develop during first and
subsequent years from lateral meristems
36
Woody Stems

Woody stems have no vascular tissue, and
instead have three distinct regions

Bark

Wood

Pith
37
Secondary Growth of Stems
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Vascular cambium:
Lateral meristem that will
produce secondary xylem
and secondary phloem in
each succeeding year.
pith
primary xylem
primary phloem
a.
b.
Periderm: As a stem
becomes woody, epidermis
is replaced by the periderm.
cortex
epidermis
pith
primary xylem
secondary xylem
vascular cambium
secondary phloem
lenticel
primary phloem
cortex
cork cambium
cork
Bark: Includes periderm and also
living secondary phloem.
Wood: Increases each
year; includes annual
rings of xylem.
c.
xylem ray
phloem ray
secondary xylem
vascular cambium
secondary phloem
cork cambium
cork
38
Bark

Bark of a tree contains cork, cork cambium, and
phloem

Bark can be removed, but it is harmful to the
plant due to lack of organic nutrient transport

Cork cells are impregnated with suberin

Gas exchange is impeded except at lenticels
39
Wood


Wood is secondary xylem that builds up year
after year

Vascular cambium dormant during winter

Annual ring is made up of spring wood and summer
wood
In older trees, inner annual rings, heartwood, no
longer function in water transport
40
Three-year-old Woody Twig
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
cork
cork cambium
cortex
phloem ray
Bark
phloem
Vascular Cambium
summer
wood
spring
wood
secondary
xylem
annual
ring
Wood
primary xylem
Pith
41
Tree Trunk
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
annual rings
a. Tree trunk,
cross-sectional view
heartwood
sapwood
vascular
cambium
phloem
cork
b. Tree trunk,
longitudinal view
© Ardea London Limited
42
Stem Diversity

Stolons:



Above-ground horizontal stems
Produce new plants when nodes touch the ground
Rhizomes:



Underground horizontal stems
Contribute to asexual reproduction
Variations:


Tubers - Enlarged portions functioning in food storage
Corms - Underground stems that produce new plants during
the next season
43
Stem Diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
rhizome
branch
axillary
bud
papery
leaves
adventitious roots
stolon
corm
axillary
bud
node
rhizome
adventitious
roots
tuber
adventitious roots
a. Stolon
b. Rhizome
c. Tuber
d. Corm
a: © Stanley Schoenberger/Grant Heilman Photography; b: © William E. Ferguson; 19c, d: © The McGraw Hill Companies, Inc./Carlyn Iverson,
photographer
44
Leaf Diversity

Blade of a leaf can be simple or compound

Leaves are adapted to environmental conditions.

Shade leaves

Spines

Climbing leaves
45
Leaf Structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
trichomes
cuticle
Water and minerals
enter leaf through xylem.
upper epidermis
palisade
mesophyll
Sugar exits leaf
through phloem.
air space
bundle sheath cell
spongy
mesophyll
lower epidermis
cuticle
leaf vein
stoma
chloroplast
central vacuole
epidermal cell
upper
epidermis
nucleus
chloroplast
palisade
mesophyll
O2 and H2O
exit leaf
through stoma.
nucleus
leaf vein
guard cell
CO2 enters leaf
through stoma.
mitochondrion
spongy
mesophyll
stoma
Leaf cell
Stoma and guard cells
lower
epidermis
100 m
SEM of leaf cross section
© Jeremy Burgess/SPL/Photo Researchers, Inc.
46
Classification of Leaves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
axillary bud
Alternate leaves,
beech
Simple leaf, magnolia
axillary buds
Palmately compound leaf,
buckeye
Whorled leaves,
bedstraw
Pinnately compound leaf
black walnut,
a. Simple versus compound leaves
Opposite leaves, maple
b. Arrangement of leaves on stem
47
Leaf Diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
stem
spine
tendril
hinged
leaves
a. Cactus, Opuntia
b. Cucumber, Cucumis
c. Venuss
’ flytrap, Dionaea
a: © Patti Murray Animals Animals/Earth Scenes; b: © Gerald & Buff Corsi/Visuals Unlimited; c: © P. Goetgheluck/Peter Arnold, Inc.
48
Review

Plant Organs
Roots
 Stems
 Leaves


Monocots vs.
Eudicots
 Epidermal Tissue
 Ground Tissue
 Vascular Tissue



Roots

Organization

Diversity
Stems

Organization

Diversity
Leaves

Organization

Diversity
49
Chapter 24: pp. 433 - 454
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10th Edition
Sylvia S. Mader
Flowering Plants:
Structure and
Organization
BIOLOGY
(Top left): © David Newman/Visuals Unlimited; (Top right): © Dwight Kuhn; (Bottom left): © Runk-Schoenberger/Grant Heilman Photography; (Bottom center): © Ardea London Ltd.;
(Bottom right): Courtesy George Ellmore, Tufts University
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
50