Download PLANT FORM AND FUNCTION

Plant Anatomy Part 2
Begins
Mr. PlantCell is back
to review the two
angiosperm clades
Mono cot and dicots
Study the diagram so
you know the
differences. For
example monocot
leaves have parallel
veins while dicots are
networked
Did you say Monocots and
Kocots? I’m a lookin’ fur
those guys.
Fibrous roots usual
Pollen grain one
opening
Tap root usual
Pollen grain three
openings
Err young lady, who are you?
Don’t you know anything Doc? That is
Mary Mary Quite Contrary. She’s
famous for gardening you know.
Actually Bugs, I’ve changed my name to help
biology students remember where plants
grow. My name is now Marystem or
properly Meristem. In a plant growth
always occurs at the meristems.
Mary, Mary quite contrary
how does your garden grow?
With silver bells and cockle shells
and pretty maids all in a row
In Greek Meristos means
divisible.
So wherever a plant grows, there’s a MERISTEM?
Where’s the meristem on
this twig?
If-fen I was to carve
my initials in this
tree, years later
would they be high
up in the tree?
How do the
branches
reaching to the
sides grow?
That’s right.
This is an apical meristem
located in the terminal bud.
It causes growth at the tip
and an increase in plant
height. This is described as
PRIMARY GROWTH. It’s how
the tree gets taller.
No Sam. The initials would still be at
the same level because the tree only
grows at the apical meristems on the
tips of the branches.
Those are axillary buds and they have
apical meristems too.
They also
use apical
meristems
and grow at
the tips. It’s
still called
PRIMARY
GROWTH.
How’s about
tree roots. How
do they grow?
Heh. What’ s the big deal with
digging up my burrow? A rabbit’s
got to have a home you know. Say
Sam, I think your lateral meristem is
showing.
APICAL MERISTEMS - tips of roots and shoots
-primary growth – stem and root elongation
-both woody and herbaceous(non woody) plants
What’s this lateral meristem?
Woody plants grow wider due to lateral meristems.
This is called SECONDARY GROWTH. So a tree trunk
grows fatter (wider) due to this.
That’s right doc and
plants grow wider
using the CAMBIUM
to produce the new
cells.
VASCULAR CAMBIUM- secondary xylem and phloem
CORK CAMBIUM- periderm
Hold still while I give
Cork cambium (innermost
layer of the bark) makes
the PERIDERM --BARK
Peri
mean
circle,
around.
It covers
stem
you a periderm I
mean perm. I was told
that a monster’s BARK
is worse than it’s bite. I
think Monsters are the
most innteresting
people. You never meet
more innteresting people in my
job than monsters.
Your initial is in the meristem called the cork cambium. I carved it there for
ya. See I’m a learning somethin’. Carvin’ it on the bark makes it a derivative
Here is a meristem. It remains embryonic
and always continues to divide and make
new cells. Cells that remain dividing in the
meristem are called INITIALS, while those
that separate and become specialized are
called DERIVATIVES
How`s about leaves. How do they grow?
Year 2
terminal
bud
scar
Year 1
terminal
bud
scar
Two bud scars and
the current terminal
bud means this is 3
years old.
Leaves grow from the apical
meristem of the shoot apex(terminal
bud). This is also the region where
the stem elongates to make the
branches longer. Nodes are the
locations on the stem where new
leaves sprout. Lateral buds also
produce leaves.
Be careful. Lateral buds
are not lateral meristems.
I do not grow from lateral
meristems!!
I’ve got a question. There’s this Bill guy who said
somethin’ about determinate and indeterminate
growth. He said it so fast and with so many
distractions I never understood what he meant.
Maybe you can help me understand .
INDETERMINATE GROWTH means the
tissues continue to grow. Ex. Tree trunks
continue to grow taller and wider
throughout their lives.
DETERMINATE GROWTH means the
tissues stop growing. Example –Leaves
grow to a certain size and stop.
A leaf trace is the vascular bundle that
extends into the leaf. Bundle sheaths
surround the vascular bundles in leaves
The trunk of a
tree is the
tree’s version
of a stem
ROOT CROSS SECTION – DIFFERENCES
BETWEEN MONOCOT AND DICOT
The Stele is a fancy name for the vascular
cylinder in the middle of the root. In the
dicot you can see it in the center
There’s a Stele in this monocot
root here too. It’s inside the dark
inner circle.
ROOTS
Let’s take a closer look at the stele
I’m gonna think of it like a steel pipe.
Water and sugar water flow inside
the pipe in the xylem and phloem.
endodermis
xylem
Stele
Dicots roots have a cross
pattern of Xylem
Gymnosperms also
Jesus Di ed on the
CROSS for us. Connect
DICOT TO CROSS
pattern in dicot roots.
Monocots have a pattern of large
xylem tubes in a broken ring
The dark layer is the ENDODERMISimportant in regulation of mineral and water
uptake by the root. Casparian strip blocks
passage of minerals/water so they must pass
through endodermal plasma membrane to
enter vascular system
ROOTS
The phloem occurs in between the xylem in
both the monocot and dicot systems
I also noticed a PERICYCLE thing
inside the stele. What it that?
The pericycle is the
outermost vascular
cylinder layer that can
form into lateral root
outgrowths and
connect that new root
to the existing plumbing
(vascular system)
ROOTS
Now don’t you get the periderm and pericycle
confused or I’ll be putting bicycles in your hair.
PERIDERM = BARK
PERICYCLE =ROOT
And root hairs
are epidermal
cells that stretch
out and absorb
most water
Apical meristem
This is my root tip
apical meristem. It is
a region of dividing
cells in various
stages of mitosis. It
makes the new cells
for root growth.
Maturation
zone
Elongation
zone
The root
grows
primarily
from the
elongation
of cells and
pushes into
the soil
The root cap is at the tip and it
acts like a helmet as it pushes into
the soil. It also adds
polysaccharide slime lubrication
to the soil.
STEMS
Let`s talk about stems in more detail now. The
pictures below show the pattern of vascular tissue
for a dicot and a monocot. The dicot forms a ring
of vascular tissue, while the monocot has scattered
vascular tissue
This is my primary
growth. With
secondary growth
stems get woody.
cortex
Cortex
always mean
outer layer
pith
Dicot+
Gynmosperms
Monocot
Wood is formed as
the vascular
cambium produces
new phloem on the
outer side facing the
bark and new xylem
facing the pith in the
middle
Eventually the inner
secondary xylem
dies and turns into
wood. The growth
rate can be seen in
the annual rings.
The dark band
represents
dormancy in winter.
The ray or ray initials produce
vascular rays movin` waternutrients usin` parenchyma
The cork
cambium is a
meristem
making the
bark
protection
Count the
annual rings
to determine
the age of
the trunk.
Between
rings it is
spring then
summer
xylem
Lenticels provide a mechanism of gas exchange
for air to penetrate into the tree trunk
The phloem
is always just
underneath
the
periderm
The
heartwood
is the
gummed
up xylem
So what happens to our tree when vermin
like our rabbit friend eat all the bark around
the stem of some fruit trees I planted
I hate to say it Sam, but your little fruit trees are
going to die. Since the phloem has been eaten, it
cannot transport any sugar nutrition down to the
roots. Cells in the roots need energy, there is no
photosynthesis in the ground, and they burn
sugars just like we do in metabolism. If there is no
sugar, metabolism stops and they die.
That`s different Sam, because the phloem is still intact on
the sides of the tree. Most of the inner xylem , wood, is
dead anyway. Back to your fruit trees, once the roots
die, the water does not conduct to the leaves and the
entire plant is doomed.
But I seen holes in
trees in Yosemite
National Park that you
could drive cars
through. They`re
doin`just fine
Plant Anatomy
I hates rabbits.
Ends
I think Sam and Mary
like each other.
Imagine, meeting on
a power-point like
that. It`s worse than
E-harmony