Download Plant Tissues

Plant Tissues
The Form and Function of Plants
Learning objectives
• Students are able to discuss the plant
body – root & shoot systems
• Students are able to describe the
different kinds of plant tissues
The "Typical" Plant Body
1) The Root System
-Anchor the plant in the soil
-Absorb water and nutrients
-Conduct water and nutrients
-Food Storage
2) The Shoot System
-Elevates the plant above the
soil
-Photosynthesize
-Reproduce
-Disperse food & conduct
water
Tissues of the plant body
• A tissue is a group of cells that forms a
structural and functional unit
• Some plant tissues are simple, whereas
others are complex
Simple & Complex Tissues
• Simple – one kind of cell
• Complex – two or more kinds of cells
Three tissue systems
(in vascular plants) based on functions
1. Dermal tissue system
2. Ground tissue system
3. Vascular tissue system
 Ground tissue
-photosynthesis
-storage
-support
Vascular tissue
-conduction of
materials
Dermal tissue
-protections
(based on functions)
The ground tissue system
• Composed of 3 simple tissues
1. Parenchyma – thin primary cell walls
2. Collenchyma – unevenly thickened
primary cell walls
3. Sclerenchyma – both primary and thick
secondary cell walls
Parenchyma cells
-Unspecialized, living, and
metabolizing cells (found
throughout the body)
-Functions: photosynthesis,
storage, secretions, and
differentiation when injured
Collenchyma cells
-Uneven primary cell walls (occur as long strands near
stem surfaces and along leaf veins)
-Function: support (flexibility)
Sclerenchyma cells
- often dead cells & thickening secondary cell walls
(occur several areas of the plant body)
- 2 types of sclerenchyma cells: Sclereids & Fibers
-Function: support the body
Fibers
-Long &
tapered cells
-Often occur
in groups
Sclereids
-Short & varied in
shape
The vascular tissue system
• Composed of two
complex tissues
1. Xylem conducts
water and
dissolved minerals
2. Phloem conducts
food materials
Xylem
• Composed of Tracheids, vessel
elements, parenchyma cells, fibers
• Conducting cells are tracheids & vessel
elements collectively called tracheary
element
Tracheids and Vessel Elements
as water conducting cells
pit
Tracheids
-Water pass through pits
-Less efficient than vessel
elements
Vessel
elements
-Hollow with
perforations at
end walls
-Wider &
shorter than
tracheids
-One cell
stacked on top
of the other
-Water
movement: updown & sideway
Tracheary Elements (Conducting Sclerenchyma)
Perforations
(Only vessel
elements)
Bordered pit
Annular
Helical
2nd 2nd cellScalariform
Reticulate 2nd Pitted 2nd cell
cell walls walls 2nd cell walls
cell walls
walls
A & B = bordered pit
1 = secondary wall
2 & 3= primary wall
4 = pit membrane
5 = pit
6 = border
Xylem
Vessel member: angiosperm
Tracheid: Gymnosperm
Phloem
• Composed of Sieve-tube
elements, companion cells,
parenchyma cells, fibers
• Conducting cells are
sieve-tube elements
Food materials are
conducted in solution
– that is, dissolved in
water through the
sieve-tube elements
Sieve-Tube Members as Food
Conducting Cells
Sieve-tube
elements
–long & thin cells
-stacked end on end
with sieve plants
-Alive at maturity
but many organelles,
including nucleus
absent
1
Sieve tube member
Which makes up vessel of
phloem. They loss of most
organelles but are still
alive
2
Companion cell
A cell adjacent to the
sieve tube cell that keep
the sieve cell tube alive
Dermal tissue system
• Consists of two complex tissues:
epidermis & periderm
• Function: protective covering
In herbaceous plants
• The dermal tissue
system is a layer
of epidermis
Epidermis as a complex tissue
• Generally contain no
chloroplasts
• Transparent to light
• Coated by cuticle
• Some modified into
guard cells
• Some modified into
trichome
• Some modified into
root hairs
Trichome
Root hair
Guard cells
in leaf
In woody plants
• Epidermis initially
produced but split
apart when 2nd growth
occurred
• Epidermis replaced by
several layers of
periderm
Tissue system
1. Ground tissue
system
2. Vascular tissue
system
3. Dermal tissue
system
Tissues
Cell types
Parenchyma tissue
Parenchyma cells
Collenchyma tissue
Collenchyma cells
Sclerenchyma
tissue
Sclerenchyma cells (sclereids,
fibers)
Xylem
Tracheids, vessel elements,
parenchyma cells, fibers
Phloem
Sieve-tube elements,
companion cells, parenchyma
cells, fibers
Epidermis
Parenchyma cells, guard cells,
trichomes
Periderm
Cork cells, cork cambium cells,
cork parenchyma
References
• เอกสารประกอบการสอนหัวข้อ Plant Tissue โดย Dr. Vasakorn
Bullangpoti มหาวิทยาลัยเกษตรศาสตร์
• Berg, L. R. 2008. Introductory Botany: Plants,
people, and the environment. 2nd ed. Thomson
Brooks/ Cole. 622 pp.
• Mauseth, J. D. 2009. Botany: an introduction to
plant biology. 4th ed. Jones and Bartlett Publishers,
LLC. 624 pp.