Plant Form and Function
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Transcript Plant Form and Function
Plant Form and Function
Structure, Growth, and Development
The plant body has a
hierarchy of organs, tissues,
and cells
There are three
basic plant
organs:
Roots
Stems
Leaves
Roots
Multicellular organs with important
functions
– Anchoring the plant
– Absorbing minerals and water
– Storing organic nutrients
Type
– Fibrous Roots
– Tap Roots
– Mycorrhizae
– fungus that forms a symbiotic
relationship with some plants
Shoot System:
Stems and
Leaves
Reproductive shoot (flower)
Apical bud
Node
Internode
Apical
bud
Stems – function
primarily to display
the leaves.
Terminal Bud –
area of growth at
the top end of
stem
Axillary Buds –
area of growth
located in the V
area between the
leaf and the stem
(branches)
Leaves – main
photosynthetic
organ in plants
Vegetative
shoot
Leaf
Shoot
system
Blade
Petiole
Axillary
bud
Stem
Taproot
Lateral
branch
roots
Root
system
There are three basic groups
of plant tissues:
Dermal Tissue
Single layer of closely packed
cells
Protects plant against water loss
and invasion by pathogens and
viruses
Cuticle – waxy layer in leaves
Vascular Tissue
Xylem and phloem
Ground Tissue
Any tissue that’s not Dermal or
Vascular tissue
Pith – ground tissue located
inside vascular tissue
Cortex – ground tissue located
outside the vascular tissue
5 Major Cell Types
Parenchyma
Most abundant
present throughout plant
most metabolism (photosynthesis)
Collenchyma
Grouped in cylinders, supports growing parts of
plant
Strings of celery (vascular tissue) is supported
by collenchyma cells
Sclerenchyma
Exists in parts of the plant that are no longer
growing
Tough cell walls utilized for support
Xylem
Phloem
Fig. 35-10a
Parenchyma cells in Elodea leaf,
with chloroplasts (LM)
60 µm
Fig. 35-10b
5 µm
Collenchyma cells (in Helianthus stem) (LM)
Fig. 35-10c
5 µm
Sclereid cells in pear (LM)
25 µm
Cell wall
Fiber cells (cross section from ash tree) (LM)
Fig. 35-10d
Vessel
Tracheids
100 µm
Pits
Tracheids and vessels
(colorized SEM)
Perforation
plate
Vessel
element
Vessel elements, with
perforated end walls
Tracheids
Fig. 35-10e
Sieve-tube elements:
longitudinal view (LM)
3 µm
Sieve plate
Sieve-tube element (left)
and companion cell:
cross section (TEM)
Companion
cells
Sieve-tube
elements
Plasmodesma
Sieve
plate
30 µm
10 µm
Nucleus of
companion
cells
Sieve-tube elements:
longitudinal view
Sieve plate with pores (SEM)
Meristems generate cells for new organs
Apical meristems
Are located at the
tips of roots and in
buds of shoots.
Sites of cell division
that allow plants to
grow in length
(primary growth)
Lateral meristems
results in growth
which thickens the
shoots and roots
(secondary growth)
Primary Growth
lengthens roots and
shoots
Zone of cell division
Includes apical
meristem
Cortex
Vascular cylinder
Epidermis
Key
to labels
Dermal
Root hair
Zone of
differentiation
Ground
Vascular
New cells produces
Zone of
elongation
Root cap is located
in root
Zone of elongation
Elongation of cells
Apical
meristem
Zone of maturation
Cell differentiation
Cell become
functionally mature
Root cap
100 µm
Zone of cell
division
Secondary Growth add girth to stems
and roots in woody plants
Two lateral meristems
Vascular cambrium
Produces secondary
xylem (wood)
Secondary phloem
Cork cambrium
Produces tough
covering that replaces
epidermis early in
secondary growth
Bark includes all the
tissues outside the
vascular cambrium.
Growth, morphogenesis, and
differentiation produce the plant
body
Morphogenesis
development of
body form and
organization.
This is the process
of cell
specialization