Transcript Plant Tissue - Cloudfront.net

Figure 35.10 Review of General Plant Cell Structure
Shoot and Root
Systems
Shoot system
- produces sugars by
photosynthesis
- carries out
reproduction
Root system
Shoot
System
- anchors the plant
- penetrates the soil
and absorbs water
and minerals
- stores food
Root
System
Shoot and root
systems are
interdependent
water &
minerals
sugar
SHOOT SYSTEM
ROOT SYSTEM
Plant Tissue
Systems
• Ground tissue
system
• Vascular tissue
system
• Dermal tissue
system
EPIDERMIS
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM
Meristems – Where Cells For New
Organs Originate
• Regions where cell divisions produce
plant growth
• Apical meristems
– Lengthen stems and roots
– Responsible for primary growth
• Lateral meristems
– Increase width of stems
– Responsible for secondary growth
Apical Meristems
Lengthen shoots and
roots
activity at
meristems
Cells that form at apical
meristems:
new cells
elongate
and start to
differentiate
into primary
tissues
protoderm  epidermis
ground meristem 
ground tissues
procambium  primary
vascular tissues
Lateral Meristems
Increases girth of older roots and stems
Cylindrical arrays of cells
vascular cambium  secondary vascular tissues
periderm  cork
cambium
thickening
Figure 35.7 The three tissue systems
The Three
Tissue
Systems
in Plants
Simple Tissues
Made up of only one
type of cell
Parenchyma
Collenchyma
Sclerenchyma
Morphology of Three Simple Tissue
Types
parenchyma
collenchyma
sclerenchyma
Figure 35.11 The three major categories of plant cells
Parenchyma: A Simple
Tissue
• Comprises most of a plant’s soft
primary growth
• Cells are pliable, thin walled, many
sided
• Cells remain alive at maturity
and retain capacity to divide
• Mesophyll is a type of
parenchyma that contains
chloroplasts
Collenchyma: A Simple
Tissue
• Specialized for support for primary
tissues
• Cells are elongated, with walls
(especially corners)
thickened with pectin
• Makes stems strong
but pliable
• Cells are alive at maturity
Sclerenchyma: A Simple
Tissue
• Supports mature plant parts
• Protects many seeds
• Cells have thick, lignified walls and are
dead at maturity
• Two types:
– Fibers: Long, tapered
– cells
– Sclereids: Stubbier cells
Complex Tissues
Composed of a mix of cell types
Xylem
Phloem
Epidermis
Xylem
• Conducts
water and
dissolved
minerals
• Conducting
cells are dead
and hollow at
maturity
tracheids
vessel
member
Figure 35.8 Water-conducting cells of xylem
Phloem:
A Complex Vascular Tissue
sieve plate
• Transports sugars
• Main conducting
cells are sievetube members
• Companion cells
assist in the
loading of sugars
sieve-tube
member
companion
cell
Figure 35.9 Food-conducting cells of the phloem
Figure 36.17 Pressure flow in a sieve tube
Epidermis:
A Complex Plant Tissue
- Covers
and protects plant
surfaces
- Secretes a waxy,
waterproof cuticle
-In plants with
secondary growth,
periderm replaces
epidermis
Monocots and Dicots –
same tissues, different
features
1 cotyledon
4 or 5 floral
parts
3 floral
parts
Parallel veins
1 pore
Vascular
bundles
in ring
2 cotyledons
Netlike veins
3 pores
Vascular
bundles
dispersed
Stems –
organs consisting of an alternating
system of nodes, the points at which
leaves are attached, and internodes,
the stem segments between nodes.
• the main functions of the stems include
conducting sugars and water and holding
leaves up into the sunlight
Monocot and Dicot Stems (Two Divisions of
Angiosperms)
Dicot Stem
Monocot Stem
Bud = undeveloped shoot of
meristematic tissue
Leaves
Internode
spaces between
leaf attachments
Axillary bud at node
(can form lateral
shoots)
Longitudinal section of terminal bud
Shoot
Development
shoot apical
meristem
procambrium
protoderm
cortex
procambrium
pith
primary xylem
ground
meristem
primary phloem
Internal Structure of a
Dicot Stem
- Outermost layer is epidermis
- Cortex lies beneath epidermis
- Ring of vascular bundles
separates the cortex from the
pith
- The pith lies in the center of
the stem
Internal
Structure
of a
Monocot
Stem
• The
vascular
bundles are
scattered
throughout the
ground tissue
• No division of
ground tissue into
cortex and pith
Secondary Growth
• Occurs in perennials
• A ring of vascular cambium produces
secondary xylem and phloem
• Wood is the accumulation of these
secondary tissues, especially xylem
Woody Stem
periderm
secondary
(consists of
phloem
cork, cork
cambium,
and secondary
cortex)
BARK
vascular cambium
SAPWOOD
HEARTWOOD
Figure 35.23 Anatomy of a tree trunk
Annual Rings
• Concentric rings of secondary xylem
• Alternating bands of early and late
wood
• Early wood
–Xylem cells with large diameter, thin
walls
• Late wood
–Xylem cells with smaller diameter,
thicker walls
Types of Wood
• Hardwood (oak, hickory)
–Dicot wood
–Xylem composed of vessels,
tracheids, and fibers
• Softwood (pine, redwood)
–Gymnosperm wood
–Xylem composed mostly of
tracheids
–Grows more quickly
Adapted for Photosynthesis
• Leaves are usually thin
– High surface area-to-volume ratio
– Promotes diffusion of carbon dioxide in,
oxygen out
• Leaves are arranged to capture sunlight
– Are held perpendicular to rays of sun
– Arrange so they don’t shade one another
Leaf Structure
UPPER
EPIDERMIS
cuticle
PALISADE
MESOPHYLL
xylem
SPONGY
MESOPHYLL
phloem
LOWER
EPIDERMIS
O2
CO2
one stoma
Stoma with
guard cells
Figure 35.19 Leaf anatomy
Mesophyll:
Photosynthetic Tissue
• A type of parenchyma
tissue
• Cells have chloroplasts
• Two layers in dicots
–Palisade mesophyll
–Spongy mesophyll
Collenchyma
Parenchyma
Leaf Veins: Vascular
Bundles
• Xylem and phloem –
often strengthened with
fibers
• In dicots, veins are netlike
• In monocots, they are
parallel
Root
Structure
• Root cap covers tip
• Apical meristem
produces the cap
• Cell divisions at the
apical meristem cause
the root to lengthen
• Farther up, cells
differentiate and
mature
root apical
meristem
root cap
Tap
Fibrous
Root Systems
Lateral Roots
grow from the
Tap Root
Primary Growth of a Root
epidermis
endodermis
cortex
pericycle
root hair
phloem
xylem
cortex
epidermis
endodermis
pericycle
xylem
phloem
Cross Section of a Root
Internal Structure of a Root
• Outermost layer is epidermis
• Root cortex is beneath the epidermis
• Endodermis, then pericycle surround
the vascular cylinder
• In some plants, there is a central pith
Root Hairs and Lateral
Roots
• Both increase the surface area
of a root system
• Root hairs are tiny extensions of
epidermal cells
• Lateral roots arise from the
pericycle and must push
through the cortex and
epidermis to reach the soil
new
lateral
root
Figure 35.16 The formation of lateral roots
Lateral Root
Figure 36.7 Lateral transport of minerals and water in roots
Figure 36.6 Compartments of plant cells and tissues and routes for lateral transport
Transport Proteins
in the plasma
membrane regulate
traffic between the
cytosol and the cell
wall
The symplast is the
continuum of cytosol
connected by
plasmodesmata.
The apoplast is the continuum
of cell walls and extracellular
spaces.
Figure 35.15 Organization of primary tissues in young roots
Prop
Roots
Pandanus
Tree With
Prop Roots
Prop
Roots
Buttress Roots
Banyan
Tree With
Aerial
Roots