Download Identifying Plant Tissues

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Identifying Plant
Tissues
Chapter 4
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Combining Cells to Form Tissues
! Plants
grow as cells divide to produce new
cells in areas of the plant called meristems.
! After
new cells are produced, they specialize
for certain functions, enlarging and changing
their structure to match their function.
! Cells…..tissues…..tissue
systems…..organs
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Four Main Types of Tissue Systems
! Meristematic
tissue system- contains cells
that are actively dividing to produce new
plant tissue
! Ground
tissue system- contains tissues that
make up the bulk of the plant
! Do photosynthesis
! Support
! Store food
! Repair damage
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Four Types of Tissue Systems
! Vascular
tissue system- conducts water,
minerals, and sugars throughout plant
! Dermal
tissue system- protect plant and
prevents water loss from tissues
+ Meristematic Tissues
! Meristematic
tissues are tissues where
cells are actively multiplying to provide
new cells for plant growth.
! permanent regions of active cell division
! all purpose cells
! can become any type of plant cell
! small, box-shaped, small vacuoles
+ Meristematic Tissues
! As
the cells enlarge, they begin to
differentiate, becoming specialized for
a certain function.
! Two
plant organ systems! Shoot system- above ground, supports
leaves, flower, and fruits
! Root system- underground, absorbs water
and minerals
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Meristematic Tissues
! Four
types of meristems
! Apical meristems
! Axillary buds
! Lateral meristems
! Intercalary meristems
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Meristematic Tissue - Apical
! Apical
Meristems - Found at the tips of roots
and shoots. Plants get taller, and roots get
longer, from their tips.
! Increase in length as the apical meristems
produce new cells (primary growth)
! Divide to produce new cells, which elongate,
making roots get longer and shoots get taller.
! Primary Meristems
! Protoderm
! Ground Meristem
! Procambium
+ Meristematic Tissue – Apical
! Once
cells elongate and differentiate
into a particular cell type, they usually
can’t divide any more due to their rigid cell
walls.
! Meristematic
cells, however, continue to
divide, enabling growth throughout the life
of the plant.
! Indeterminate
growth- keeps growing
throughout life
! Determinate growth- stops growing when
reaches maturity
+ Meristematic Tissues - Lateral
! Lateral
meristems are thin cylinders of
tissue that form in mature regions of
shoots and roots of many plants,
especially those that produce woody
tissue.
! They
divide to produce secondary
growth, growth that increases the
diameter [girth] of a shoot [stem or
trunk] or root.
+ Meristematic Tissues - Lateral
! Plants
have two types of lateral
meristems.
! Vascular
Cambium – Produces new vascular
tissues that function primarily in support
and conduction.
! Thin cylindrical cells.
! Cork Cambium - Lies outside vascular
cambium just inside the outer bark of woody
plants.
Meristems and Growth
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Meristematic Tissues - Axillary
! Axillary
Buds
-- produced as stems elongate in the angle
between the stem and the petiole of each
leaf
-- May remain dormant until apical
meristem has grown and moved away from
the axillary bud.
-- When apical meristem is far enough
away, the meristems of the axillary bud
begins to grow forming a branch.
+ Meristematic Tissue - Axillary
! Branches
can be
forced to grow
by removing the
apical meristem
which wakes up
the axillary
meristem of the
main shoot.
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Meristematic Tissues
! Grasses
and related plants do not have
vascular cambium or cork cambium, but do
have apical meristems in the vicinity of the
nodes.
! Intercalary meristems
! Develop at intervals along stems where
they add to stem length- cells get added
to the middle to increase length
! This is why you can mow grass and the
grass will continue to get longer.
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Intercalary Meristem