Download Plant growth

10/2/2014
o Plants take up water and minerals from below
ground
o Plants take up CO2 and light from above
ground
THREE BASIC PLANT ORGANS
ROOTS
o Roots
o Stems
o Leaves
o Anchor plant
o Absorb water and minerals
o Store carbohydrates
LARGE AMOUNT OF ABSORPTION OCCURS
THROUGH ROOT HAIRS
MODIFIED
ROOTS
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STEMS
APICAL DOMINANCE
o Raise and
separate leaves
o Support plant
o Conduct materials
from roots to
leaves
o Inhibition of lateral
buds by an apical
bud
MODIFIED STEMS
LEAVES
o Main
photosynthetic
organ
Consist of blade
and petiole
Can be simple or
compound
MODIFIED LEAVES
PLANT TISSUES
o Dermal
o Vascular
o Ground
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DERMAL TISSUE SYSTEM
o Epidermis with waxy cuticle
o Periderm replaces epidermis in woody plants
VASCULAR TISSUE
o Xylem conducts water and minerals upward
o Phloem conducts sugars from where they are
produced to where they are needed
TRICHOMES
o Epidermal
cells that
can provide
protection
from
herbivores
XYLEM
o Dead at
maturity
o Xylem and phloem are bundled in the stele
PHLOEM
o Partially
alive at
maturity
o Companion
cells
provide
cellular
support
GROUND TISSUE
o All tissue that is neither
epidermal nor vascular
o Internal vascular tissue is
pith
o External to vascular
tissue is cortex
o Ground tissue includes
cells specialized for
storage, photosynthesis,
and support
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PARENCHYMA
COLLENCHYMA
o Thin-walled with
large vacuole
o Intercellular
spaces may be
present
o Most common
type of ground
tissue
o Flexible support
with unevenly
thickened cell
walls
SCLERENCHYMA
o Rigid support
o Thick secondary walls with lignin
PLANTS HAVE INDETERMINATE GROWTH
o Growth in plants is not limited to embryonic or
juvenile periods
o Animals show determinate growth, as do some
plant organs such as flowers, thorns and
leaves
o Cell division and growth occurs in meristems
 Apical meristems initiate primary growth
 Lateral meristems initiate secondary growth (wood)
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TYPES OF LIFE CYCLES
PRIMARY ROOT GROWTH
o Annuals complete life cycle in one year
o Biennials complete life cycle in two years
o Perennials live many years
ROOT STRUCTURE
LATERAL ROOT GROWTH
PRIMARY GROWTH OF SHOOTS
STEM STRUCTURE
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LEAF STRUCTURE
SECONDARY GROWTH
o Lateral meristems add thickness to woody
plants, a process called secondary growth
o There are two lateral meristems: the vascular
cambium and the cork cambium
 The vascular cambium adds layers of vascular tissue
called secondary xylem (wood) and secondary phloem
 The cork cambium replaces the epidermis with
periderm, which is thicker and tougher
SECONDARY GROWTH INCREASES THE DIAMETER OF
STEMS AND ROOTS IN WOODY PLANTS
o Secondary growth occurs in stems and roots
of woody plants but rarely in leaves
o The secondary plant body consists of the
tissues produced by the vascular cambium
and cork cambium
o Secondary growth is characteristic of
gymnosperms and many eudicots, but not
monocots
Secondary xylem
Secondary phloem
Vascular cambium
Late wood
Early wood
Bark
Cork
cambium
Periderm
0.5 mm
Cork
Vascular ray
0.5 mm
Growth ring
(b) Cross section of a three-yearold Tilia (linden) stem (LM)
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EXAM 2
AN EXAMPLE OF A LIVING PLANT CELL THAT
LACKS A NUCLEUS WOULD BE
NEW SHOOTS ON AN ACTIVELY GROWING STEM
COME FROM
a)
b)
c)
d)
e)
a)
b)
c)
d)
20% 20% 20% 20% 20%
lls
.
tis
su
e.
ce
ty
l
a
ym
hy
po
co
nc
h
20%
20%
.
20%
ba
rk
em
ph
lo
m
18
.5
m
11
.5
m
2.
5
m
m
1.
5
1.
0
20%
lt
is s
ue
.
20%
ica
phloem.
xylem.
pith.
cortical tissue.
bark.
.
a)
b)
c)
d)
e)
co
rt
20%
th
.
20%
pi
20%
.
20%
1.0 m
1.5 m
2.5 m
11.5 m
18.5 m
em
20%
A.
B.
C.
D.
E.
THE INCREASE IN GIRTH OF WOODY PLANTS IS
PRIMARILY DUE TO THE INCREASE IN THE
PRODUCTION OF
xy
l
YOU CARVE YOUR INITIALS 1.5 M ABOVE THE GROUND
IN A 10-M-TALL TREE SAPLING. IF YOU RETURN 20
YEARS LATER AND THE TREE IS 25 M TALL, YOUR
INITIALS WILL BE _____ ABOVE THE GROUND.
sc
le
re
ep
a
sie
a
al
id
er
m
ar
st
ip
ul
yb
ud
s.
es
.
fib
er
m
.
es
op
hy
ll
c
ve
e ll
.
tu
be
el
em
en
t.
stipules.
axillary buds.
epidermal cells.
sclerenchyma
tissue.
e) hypocotyl tissue.
a
co
m
a
pa
n
gu
a
io
n
rd
ce
ce
ll.
ll.
20% 20% 20% 20% 20%
ax
ill
a guard cell.
a companion cell.
fiber.
a mesophyll cell.
a sieve tube
element.
t is
su
e.
USING TREE RINGS TO STUDY HISTORY
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THINK ABOUT THE STRUCTURE OF A ROOT TIP. IN
WHICH REGION WOULD YOU EXPECT THE MAJORITY
OF WATER AND NUTRIENT UPTAKE TO OCCUR?
A STEM CROSS SECTION WITH DISPERSED
VASCULAR BUNDLES WOULD MOST LIKELY BE
SEEN IN
A. Root cap
B. Apical lens
(meristem)
C. Zone of cell division
D. Zone of cell
elongation
E. Zone of cell
maturation
fern plants.
moss plants.
pine trees.
maple trees.
corn plants
20%
20%
20%
20%
tio
es
.
an
ts
pl
co
rn
es
.
tre
ap
le
pi
ne
tre
lan
an
t
pl
n
os
sp
m
fe
r
Zo
ne
m
s.
lm
ts
.
at
ur
a
ng
a
lo
le
el
el
of
c
of
c
20%
n
n
tio
sio
ivi
ld
el
of
c
Zo
ne
Ap
ic a
Zo
ne
l le
ns
(m
er
Ro
ist
ot
c
em
n
)
ap
20% 20% 20% 20% 20%
WHICH OF THE FOLLOWING TISSUE TYPES ARE
UNIQUE TO LEAVES?
ist
M
er
M
es
op
hy
l
m
20%
em
20%
l
20%
Xy
le
20%
te
x
20%
Co
r
Stomata
Cortex
Xylem
Mesophyll
Meristem
St
om
at
a
A.
B.
C.
D.
E.
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