Transcript Document

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 35
Plant Structure, Growth, and
Development
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Concept 35.1: Plants have a hierarchical
organization consisting of organs, tissues,
and cells
• Plants have organs composed of different tissues,
which in turn are composed of different cell types
• A tissue is a group of cells consisting of one or
more cell types that together perform a specialized
function
• An organ consists of several types of tissues that
together carry out particular functions
© 2011 Pearson Education, Inc.
Figure 35.2
Reproductive shoot (flower)
Apical bud
Node
Internode
Apical bud
Vegetative shoot
Leaf
Axillary bud
Shoot
system
Blade
Petiole
Stem
Taproot
Lateral (branch)
roots
Root
system
Roots
• A root is an organ with important functions:
– Anchoring the plant
– Absorbing minerals and water
– Storing carbohydrates
© 2011 Pearson Education, Inc.
Figure 35.4
“Strangling”
aerial roots
Storage
roots
Prop roots
Buttress
roots
Pneumatophores
Stems
• A stem is an organ consisting of
– An alternating system of nodes, the points at
which leaves are attached
– Internodes, the stem segments between nodes
© 2011 Pearson Education, Inc.
Figure 35.5
Rhizomes
Rhizome
Root
Bulbs
Storage leaves
Stem
Stolons
Stolon
Tubers
• Monocots and eudicots differ in the arrangement
of veins, the vascular tissue of leaves
– Most monocots have parallel veins
– Most eudicots have branching veins
• In classifying angiosperms, taxonomists may use
leaf morphology as a criterion
© 2011 Pearson Education, Inc.
Figure 35.6
Simple leaf
Axillary
bud
Compound leaf
Leaflet
Petiole
Doubly
compound leaf
Petiole
Axillary
bud
Petiole
Axillary
bud
Leaflet
Figure 35.7
Tendrils
Spines
Storage
leaves
Reproductive
leaves
Bracts
Dermal, Vascular, and Ground Tissues
• Each plant organ has dermal, vascular, and
ground tissues
• Each of these three categories forms a tissue
system
• Each tissue system is continuous throughout the
plant
© 2011 Pearson Education, Inc.
Figure 35.8
Dermal
tissue
Ground
tissue
Vascular
tissue
Common Types of Plant Cells
• Like any multicellular organism, a plant is
characterized by cellular differentiation, the
specialization of cells in structure and function
© 2011 Pearson Education, Inc.
• The major types of plant cells are:
–
–
–
–
–
Parenchyma
Collenchyma
Sclerenchyma
Water-conducting cells of the xylem
Sugar-conducting cells of the phloem
© 2011 Pearson Education, Inc.
Parenchyma Cells
•
Mature parenchyma cells
–
–
–
–
–
Have thin and flexible primary walls
Lack secondary walls
Are the least specialized
Perform the most metabolic functions
Retain the ability to divide and differentiate
© 2011 Pearson Education, Inc.
Figure 35.10a
Parenchyma cells in Elodea
leaf, with chloroplasts (LM)
60 m
Collenchyma Cells
• Collenchyma cells are grouped in strands and
help support young parts of the plant shoot
• They have thicker and uneven cell walls
• They lack secondary walls
• These cells provide flexible support without
restraining growth
© 2011 Pearson Education, Inc.
Figure 35.10b
Collenchyma cells
(in Helianthus stem) (LM)
5 m
Sclerenchyma Cells
• Sclerenchyma cells are rigid because of thick
secondary walls strengthened with lignin
• They are dead at functional maturity
• There are two types:
– Sclereids are short and irregular in shape and
have thick lignified secondary walls
– Fibers are long and slender and arranged in
threads
© 2011 Pearson Education, Inc.
Figure 35.10c
5 m
Sclereid cells in pear (LM)
25 m
Cell wall
Fiber cells (cross section from ash tree) (LM)
Water-Conducting Cells of the Xylem
• The two types of water-conducting cells,
tracheids and vessel elements, are dead at
maturity
• Tracheids are found in the xylem of all vascular
plants
© 2011 Pearson Education, Inc.
Figure 35.10d
Vessel
Tracheids
100 m
Tracheids and vessels
(colorized SEM)
Pits
Perforation
plate
Vessel
element
Vessel elements, with
perforated end walls
Tracheids
Figure 35.10da
Vessel
Tracheids
100 m
Tracheids and vessels
(colorized SEM)
Sugar-Conducting Cells of the Phloem
• Sieve-tube elements are alive at functional
maturity, though they lack organelles
• Sieve plates are the porous end walls that allow
fluid to flow between cells along the sieve tube
• Each sieve-tube element has a companion cell
whose nucleus and ribosomes serve both cells
© 2011 Pearson Education, Inc.
Figure 35.10e
3 m
Sieve-tube elements:
longitudinal view (LM)
Sieve plate
Sieve-tube element (left)
Companion
and companion cell:
cells
cross section (TEM)
Sieve-tube
elements
Plasmodesma
Sieve
plate
30 m
Nucleus of
companion
cell
15 m
Sieve-tube elements:
longitudinal view
Sieve plate with pores (LM)
Primary Growth of Roots
• The root tip is covered by a root cap, which
protects the apical meristem as the root pushes
through soil
• Growth occurs just behind the root tip, in three
zones of cells:
– Zone of cell division
– Zone of elongation
– Zone of differentiation, or maturation
© 2011 Pearson Education, Inc.
Figure 35.13
Cortex
Vascular cylinder
Epidermis
Root hair
Zone of
differentiation
Key
to labels
Dermal
Ground
Vascular
Zone of
elongation
Zone of cell
division
(including
apical
meristem)
Root cap
Mitotic
cells
100 m
• The primary growth of roots produces the
epidermis, ground tissue, and vascular tissue
• In angiosperm roots, the stele is a vascular
cylinder
• In most eudicots, the xylem is starlike in
appearance with phloem between the “arms”
• In many monocots, a core of parenchyma cells is
surrounded by rings of xylem then phloem
© 2011 Pearson Education, Inc.
Figure 35.14
Epidermis
Cortex
Endodermis
Vascular
cylinder
100 m
(a) Root with xylem and
phloem in the center
(typical of eudicots)
50 m
Pericycle
Core of
parenchyma
cells
Xylem
Phloem
Endodermis
Pericycle
Xylem
Phloem
100 m
(b) Root with parenchyma in the
center (typical of monocots)
Key
to labels
Dermal
Ground
Vascular
Figure 35.14aa
Epidermis
Cortex
Endodermis
Vascular
cylinder
Key
to labels
Dermal
Ground
Vascular
Pericycle
Xylem
Phloem
100 m
(a) Root with xylem and phloem in the center
(typical of eudicots)
Figure 35.14ab
50 m
Endodermis
Pericycle
Xylem
Phloem
Key
to labels
Dermal
Ground
Vascular
Figure 35.14b
Epidermis
Key
to labels
Cortex
Dermal
Endodermis
Ground
Vascular
Vascular
cylinder
Pericycle
Core of
parenchyma
cells
Xylem
Phloem
100 m
(b) Root with parenchyma in the center
(typical of monocots)
Tissue Organization of Leaves
• The epidermis in leaves is interrupted by
stomata, which allow CO2 and O2 exchange
between the air and the photosynthetic cells in a
leaf
• Each stomatal pore is flanked by two guard
cells, which regulate its opening and closing
• The ground tissue in a leaf, called mesophyll, is
sandwiched between the upper and lower
epidermis
© 2011 Pearson Education, Inc.
Figure 35.18a
Key
to labels
Sclerenchyma
fibers
Cuticle
Dermal
Stoma
Ground
Vascular
Upper
epidermis
Palisade
mesophyll
Spongy
mesophyll
Bundlesheath
cell
Lower
epidermis
Xylem
Vein
Phloem
(a) Cutaway drawing of leaf tissues
Guard
cells
Cuticle