Angiosperm anatomy.ppt

transverse section of primary stem and root as well as T. S. secondary stem and root

1. THE PLANT BODY

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 Meristemsresult 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
cuticleand
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

11. Guard Cells and Stoma
Guard Cell
Stoma (opening)

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

16. Parenchyma Cells
Intercellular
spaces

17. Parenchyma Cells

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

19. Collenchyma Cells
Longitudinal view
Cross
section
showing
uneven
wall
thickening

20. Sclerenchyma
Two cell types
•fibers
•sclereids.
Non-living at maturity
Thickened secondary walls

21. Fibers
Elongate cells
Function in support
Leaf and stem fibers from many plants
used for cloth and rope.

22. Sclereids
Various shapes
Functions
•mechanical support and
•protection
Account for the hardness in nut shells
and the grit of pear fruit

23. Sclerenchyma
X-section of fiber showing
thick secondary wall
Fiber
Sclereid
x-section
showing
thick
secondary
wall
Sclereids

24. Sclereids

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
•Vesselelements-short, wide, with
horizontal end walls with large openings
•Both cells have secondary walls
Fibers -non-living -provide support
Parenchyma cells -metabolic activity

27. Tracheids and Vessels

28. Xylem Cells from Oak Wood

29. Primary and Secondary Xylem
Primary xylemdevelops from the
apical meristem
Secondary xylemdevelops 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 TypeCell Types Function
Dermal
Epidermis epidermal cells protection
Periderm cork cells protection
Ground
Parenchyma parenchyma cells storage,
photosynthesis
Collenchymacollenchyma cells support
Sclerenchymasclereids, fibers support,
protection

34. Plant Tissues and Cells
Tissue TypeCell Types Function
Vascular
Xylem tracheids water
vessel elements conduction
fibers support
parenchyma metabolism
Phloem sieve tube transport
member sugars
companion cellsloading
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

36. Herbaceous Dicot Stem
X
P
Epidermis
Cortex (parenchyma cells)
Pith (parenchyma
cells)
Vascular bundle
Cross-section

37. Monocot Stem
Epidermis
Ground
Tissue
Vascular bundle
Scattered
Vascular Bundles

38. Roots
Stele
Epidermis
Xylem
Cortex
Phloem
Endodermis
root
hair

39. Leaf
X
P
Epidermis
Veins
Spongy mesophyll
(parenchyma)
Palisade Mesophyll
(parenchyma)

40. Leaf from Ligustrum

41. Secondary Growth in Dicots

42. 5 Year Old Woody Dicot Stem
One
annual
ring
Periderm (cork)
Cortex
Secondary phloem
Vascular Cambium
5 Years of Secondary Xylem

43. Three Year Old Tree

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