Transcript Plant Structure and Growth

Chapter focus
Plant
structure and growth
Warning – many terms or
vocabulary words
Warning – many diagrams
Focus – structure, function,
located next to ….
Question ?
What
heading can be given to
the following groups of
words?
--------Lettuce
Peas
Beans
---------Rhubarb
Apples
Oranges
Question ?
What
is a vegetable?
What is a fruit?
Vegetables
Lettuce
Rhubarb
Fruits
Peas
Beans
Apples
Oranges
Point
Plants
have organs too,
just like animals.
Asexual organs (vegetables)
Sexual organs (fruits)
Asexual Organs
1. Stem
2. Leaf
3. Root
Stem
The
main body of the portion
above ground of a tree, shrub
or herb.
The ascending plant axis.
Stem Functions
Support
of other plant organs.
Ps.
Storage
(water and food).
Leaf
Lateral
outgrowths of the stem
axis.
Primary photosynthetic organs.
Function:
Photosynthesis
Storage
Root
The
descending axis of a plant,
normally below ground.
Functions:
Anchorage.
Absorption
Storage.
of water and minerals.
Sexual Organs
1. Flowers
2. Fruits
3. Seeds
Flowers
Modified
leaves grouped
together on a stem.
Sexual reproductive organs.
Function:
Sexual
Reproduction
Fruit
A
mature ovary, sometimes
including other floral parts.
Function:
Seed
dispersal
Seed protection
Seed
Mature
ovule containing the
embryo and nutrient tissues.
Function:
Dispersal
unit in sexual
reproduction.
Plant Cell Types
Differentiated
by the type and
thickness of the cell wall.
1. Parenchyma (soft tissue)
2. Collenchyma (glue tissue)
3. Sclerenchyma (hard tissue)
Parenchyma Cells
Primary
wall
only.
Thin cell wall.
Alive when
mature,
“typical" plant
cell.
Functions
Ps
Storage
"Filler"
cells
Cell division (mitosis)
Collenchyma
 Primary
wall only.
 Wall is thickened,
especially in the
corners.
 Alive when
mature.
Function
Support
of non-woody plant
parts.
Ex: veins, stems.
Sclerenchyma
Secondary
wall present.
Wall
strengthened
with lignin.
Dead when
mature.
Sclerenchyma Types
1. Fibers
2. Sclereids
3. Tracheids
4. Vessel Elements
Fibers
Elongated
thin
cells used for
support.
Ex: Hemp
fibers
Sclereids
Used
for hard
dense areas
and support.
Ex: Nut shells,
seed coats
Tracheids
Spindle
shaped cells
with pits in the
cell walls.
Used for water
transportation.
Vessel
Fiber
Vessel Elements
Wide
stocky
cells with pits
in the side
walls; lack end
walls.
Used for water
transportation.
Plant Tissues
Can
be named by several
methods:
Ex:
Cell Location
Cell Origin
Cell Function
Point
The
same cell can have
several tissue names
depending on the criteria for
naming.
Main Tissue Systems
1. Dermal
2. Vascular
3. Ground
Dermal Tissue
Epidermis
or "skin" of the
plant.
Often has a cuticle, a waxy
coating to prevent water loss.
Functions:
Prevent
water loss.
Water absorption (root hairs).
Vascular Tissue
Made
of Xylem and Phloem.
Functions:
Transport
and support
Xylem - Water
Phloem - Food
Xylem
Phloem
Phloem
Cell – alive when
functioning, but lacks a
nucleus.
Companion Cell – alive,
controls itself and the sieve
cell.
Sieve
Ground Tissue
Tissue
between the dermal
and the vascular tissues.
Functions:
"Filler"
tissue
Ps
storage
support
Question ?
How
does plant growth and
animal growth differ ?
Animals
Whole
organism increases in
size.
Determinant Growth: grow to
a certain size, then stop.
Plants
Growth
in specialized areas
only.
Indeterminant Growth: grow
as long as they live because
the specialized areas remain
embryonic.
Plant Meristems
Perpetual
embryonic
regions.
Zones for cell
division.
Meristem Types
1. Apical growth in
length. Primary
growth.
2. Lateral/Cambiums
growth in diameter.
Secondary growth.
Comment
Some
tissues like Xylem may
be Primary or Secondary
depending on which meristem
produced the cell.
Ex:
Primary
xylem
Secondary xylem
Apical Meristem Types
1. RAM – Root Apical Meristem:
primary growth of roots.
2. SAM – Shoot Apical Meristem:
primary growth of shoots.
RAM
Located
at the
tip of each
growing root.
Protected from
the soil by the
Root Cap.
RAM
Root Cap
Protects
RAM.
Secrets a polysaccharide
lubricant for root growth.
Primary Root Zones
1. Cell Division - cells small
and embryonic.
2. Cell Elongation - cells
elongate and start to mature.
3. Cell Differentiation - cells
mature into final cell types.
Root Hairs
Extensions
of the epidermis to
increase surface area for
water absorption.
Not a true tissue.
Comment - root hairs are very
delicate and must be
continually replaced.
Root Hairs
RAM - Primary Tissues
1. Protoderm
2. Procambium
3. Ground Meristem
Protoderm
Will
mature into the
epidermis and root hairs.
Procambium Stele
Matures
into the vascular
tissues of the stele:
Xylem
Phloem
Pericycle
– site of branch roots
Ground Meristem
Matures
into the ground
tissues:
– storage tissue
Endodermis – second skin
around the stele that controls
the movement of materials
into the stele.
Cortex
Epidermis
Cortex
Stele
Endodermis
Pericycle
Xylem
Phloem
Branch Roots
Originate
from
the pericycle.
Burst their
way to the
outside.
Root Types
Taproot
Ex:
- one main root.
carrot
Fibrous
Roots - many small
roots of equal size.
Ex:
grass roots
Adventitious Roots
Roots
that develop from
other plant parts.
Ex: roots on stem cuttings
climbing roots
SAM Produces
1. Protoderm
2. Procambium
3. Ground Meristem
Comment – these tissues
mature into the same things
as seen in RAM.
SAM Differences
No
"root" cap.
Produces leaves as stem
out-growths at the nodes.
Has buds.
Buds
Apical
Meristems
protected by
modified leaves
or bud scales.
Axillary Buds
Branch Stems
Develop
from
axillary
meristems or
axillary buds.
"External"
development.
Modified Stems
1. Rhizomes
2. Stolons
3. Tubers
4. Tendrils
Rhizome
An
elongated
underground
horizontal
stem.
Ex: Iris,
many grasses
Stolon
An
elongated
above-ground
horizontal
stem.
Ex:
Strawberries
Airplane Plant
Tuber
A
muchenlarged,
short, fleshy
underground
stem tip.
Ex: Dahlia,
Potato
Tendril
A
slender coiling stem.
Ex: Clematis and other
climbing vines.
Leaves
Stem
outgrowths for Ps.
Leaf Morphology:
1. Gross
2. Fine
Gross Morphology
Blade
- the flattened portion
of a leaf.
Petiole - stalk of a leaf.
Axillary Buds
Blade
Petiole
Blade/Leaf Types
Simple
- 1 blade.
Compound - Several blades.
Nodes and Internodes
Node
- stem area where a leaf
and bud are attached.
Internode - stem area
between nodes.
Nodes
}
Internode
Fine Morphology
The
tissues within a leaf.
1. Upper Epidermis
2. Mesophyll
3. Lower Epidermis
4. Veins
Upper Epidermis
Cuticle
present.
Usually 1 cell layer thick.
Cells w/o chloroplasts .
Function: protects the
mesophyll.
Mesophyll
1. Palisade
upright cells.
2. Spongy
loosely
organized cells
with air spaces.
 Function: major
sites for Ps.
Epidermis
Epidermis
Lower Epidermis
Cuticle
present.
Usually 1 cell layer.
Cells w/o chloroplasts.
Stomata present for gas
exchange.
Stomata (mouth)
Regulated
by
Guard Cells
which have
chloroplasts.
Vein Structure
Xylem:
dorsal
Phloem: ventral
Often surrounded by bundle
sheath cells for support.
Xylem
Phloem
Bundle
Sheath Cells
Collenchyma
Homework
Read
Chapter 35, 37
No lab broadcast 3/27
Chapter 35 – Fri. 3/28
Leaf Modifications
1. Tendrils: for support
Ex: Peas
2. Bulbs: for food storage
Ex: Onion
3. Insect Catching
Ex: Carnivorous Plants
4. Flowers: thought to be
modified leaves.
Other Modifications of Leaves
Tendrils
Succulent Leaves
Spines
Bracts
Stem Vascular Tissue
– vascular bundles join
together to make a ring. Often
have secondary growth.
Monocots – vascular bundles
are scattered. No true
secondary growth.
Dicots
Secondary Growth
Growth
in diameter.
Growth from lateral
meristems or cambiums.
Cambium Types
1. Vascular – produces xylem
and phloem.
2. Cork – produces “cork”.
Vascular Cambium
Location:
between primary
xylem and phloem.
Produces: secondary xylem
and phloem.
Fibers
Phloem
Vascular Cambium
Xylem
Fibers
Vascular Cambium:
Cell Maturation
 xylem
External  phloem
The VC pushes the xylem and
phloem apart from each
other.
Internal
Result
Newest
xylem is next to the
cambium.
Oldest xylem is in the center
of stem.
Result
Newest
phloem is next to
cambium.
Oldest phloem is under the
epidermis.
Result
Xylem
accumulates over
time.
Phloem is destroyed by the
outward growth and must be
replaced yearly.
Cork Cambium
Location:
Cortex
(external to the VC).
Produces: Cork
Comment – commercial cork
is harvested from a Cork Oak.
Cork Cells
Produced
"outwardly" only.
Covered with suberin and are
dead when mature.
Function – insulation and
protection.
Epidermis
Cork
Cambium
Cortex
Phloem
Vascular
Cambium
Xylem
Fibers
Bark
All
tissues external to the VC.
Includes:
Phloem
(1 degree and 2 degree)
Cork
Cortex
Epidermis
Fiber
cells
Wood
Xylem
tissue of a dicot stem.
Comment – monocots don’t
have VC and technically don’t
produce true “wood”.
Xylem Growth
Springwood
- Large cells
Rapid growth
Summerwood - Small cells
Slow growth
Annual Rings
Formed
by the growth
difference between springwood
and summerwood.
Usually one produced per year.
Comment
Ring
size varies by climate
and growing conditions.
Rings can be used to date
wooden structures.
Summer Wood
Spring Wood
One Year’s Growth
Angiosperms
Divided
into two main types:
1. Dicotyledons or Dicots
2. Monocotyledons or Monocots
Cotyledons = seed leaves
Monocots vs. Dicots
1. Seeds and embryos
2. Leaves
3. Stems
4. Roots
5. Flowers
Seeds and Embryos
Dicots
- no endosperm.
- 2 cotyledons.
Monocots - endosperm
- 1 cotyledon
Leaves
– netted veins.
Monocots - parallel veins.
Dicots
Stems
Dicots
- ring pattern
- vascular cambium
Monocots - scattered pattern
- no vascular
cambium
Roots
Dicots
- taproot.
- xylem centermost
tissue.
Monocots - fibrous roots.
- pith centermost
tissue.
Flowers
– parts in 4's or 5's.
Monocots – parts in 3's.
Dicots
Summary
Know
the main organs of
plants and their functions.
Know the main cell types or
tissues in plants and their
functions.
Summary
Know
the structural
organization of stems, roots,
and leaves.
Know the differences
between dicots and
monocots.