2. Meristems
In flowering plants cells originate from
regions of active cell division known as
meristems.
The cells arising from meristems give
rise to the many different cell types that
make up a plant
3. Types of Meristems
Primary Meristems (also called Apical
Meristems) result in primary growth -
growth in length
Secondary Meristems result in
secondary growth which in growth in
width (increase in diameter)
4. Apical meristems
Also known as primary meristems
Found at the tips of all roots and stems
Contribute to the increase in length of
the plant which is called primary growth
Give rise to the leaves, and non-woody
stems and roots
5. Secondary Meristems
Some plants have additional meristems
that result in increases in diameter
which is secondary growth.
• Vascular cambium
• cork cambium
6. Multicellular Organisms
In multicellular organisms, certain cells
are specialized in structure and function
Tissues are specialized cells that
perform specific functions
Plants composed of three basic tissues
categories
• Dermal
• Ground
• Vascular
7. Dermal Tissue
Dermal tissues are the outermost layers
in a plant
They protect the plant
Two types of dermal tissues
• Epidermis
• Periderm
8. Epidermis
Outermost layer In
young plants and
non-woody plants
Single layer of
flatten cells
Cells secrete cutin
which makes up the
cuticle and
prevents water loss
Epidermal
Cell
Cuticle
9. Trichomes
Hairs (trichomes)
may be present on
the epidermis.
Sometime abundant
enough so leaves
look fuzzy
Trichomes may also
be glandular
Hair
Gland
10. Guard Cells and Stomata
Pores known as stomata (singular
stoma) occur on epidermis
Gases exchange occurs through
stomata
A pair of sausage-shaped cells, guard
cells, regulate the opening and closing
of the stomata
12. Periderm
In woody plants when the tree increases
in diameter, the epidermis cracks and is
replaced by periderm
The periderm consists:
• Cork cells
• Cork cambium
13. Cork Cells
Outer bark on mature trees
Dead cells with walls containing
suberin, a waterproofing fatty
substance.
Prevents water loss from underlying
tissues
Produced by cork cambium
14. Ground tissues
Major tissue of non-woody plant organs
Perform a variety of functions
The three types of ground tissue:
• Parenchyma
• Collenchyma
• Sclerenchyma
15. Parenchyma
Almost any shape or size
Loosely arranged with intercellular
spaces
Many different functions:
• Photosynthetic cells in leaves and green
stems
• Storage cells in plant organs for starch,
sugar, or water
18. Collenchyma
Support tissue in young plant organs
Found in stems, leaves, and petals
Elongated cells with unevenly thickened
primary cell walls with the walls thickest
at the corners
Found tightly packed together just
below the epidermis
25. Vascular tissues
Xylem - conducts water and minerals
from the roots upward
Phloem - transports organic materials
(sugars) synthesized by the plant
26. Xylem
Cells conducting water - non-living
• Tracheids - long thin cells with tapering
walls and numerous pits
• Vessel elements - short, wide, with
horizontal end walls with large openings
• Both cells have secondary walls
Fibers - non-living - provide support
Parenchyma cells - metabolic activity
29. Primary and Secondary Xylem
Primary xylem develops from the
apical meristem
Secondary xylem develops from the
vascular cambium.
In trees secondary xylem is very
extensive
30. Phloem
Cell Types in phloem
• Sieve Tube Members - transport sugars
• Companion Cells - loading and unloading
• Fibers - support
• Parenchyma - metabolic activity
Primary and Secondary phloem
31. Sieve Tube Member
• Living cells with
only thin primary
walls
• End walls have
sieve plates (large
pores with large
plasmodesmata)
End wall
with sieve
plate
32. Companion cells
• Specialized parenchyma cell
develops alongside a sieve tube
member
• Plasmodesmata connect it to sieve
tube member
• Loading and unloading sugars for
transport
33. Plant Tissues and Cells
Tissue Type Cell Types Function
Dermal
Epidermis epidermal cells protection
Periderm cork cells protection
Ground
Parenchyma parenchyma cells storage,
photosynthesis
Collenchyma collenchyma cells support
Sclerenchyma sclereids, fibers support,
protection
34. Plant Tissues and Cells
Tissue Type Cell Types Function
Vascular
Xylem tracheids water
vessel elements conduction
fibers support
parenchyma metabolism
Phloem sieve tube transport
member sugars
companion cells loading
fibers support
parenchyma metabolism
35. Plant Organs
Stems
• Support leaves
• Conduct water and sugars
Roots
• Anchor the plant
• Absorb water and minerals
Leaves
• Photosynthesis
• Transpiration
46. Dendrochronology
Study of tree rings has added many
fields of study
Can tell us about past climates
Can be used to date from archeological
sites artifacts
Tree ring research lab at the University
of Arizona http://www.ltrr.arizona.edu/
47. Summary
Growth, replacement of cells, and
asexual reproduction all depend on cell
division
Tissues are groups of cells that perform
a common function
Stems, roots and leaves are made up of
three basic tissue types: dermal,
ground, and vascular