1. Plant anatomy

2. From smallest to largest plants

3. What is plant anatomy?
ANATOMY: study of the structure of organisms… looking at cells, tissues

4. How can water move from
the ground
all the way
to the top
of a 100 m
tall redwood
tree?

5. Plant Anatomy: Cells Plant cells are basic building blocks
Can specialize in form and function
By working together, forming tissues, they can support each other and survive
Levels of organization
atoms > molecules > cells > tissues > organs > whole plant > pop.

6. Plant Tissues Types
All plant organs (roots, stems, leaves) are composed of the same tissue types.
There are three types of tissue:
1. Dermal – outermost layer
2. Vascular – conducting tissue, transport
3. Ground – bulk of inner layers

7. 1. Dermal tissue Epidermis is the outermost layer of cells
Like the “skin” of animals
In stems and leaves, epidermis has cuticle, a waxy layer that prevents water loss.
Root epidermis has root hairs, for water and nutrient absorption

8. 2. Vascular tissue
Transports water and organic materials (sugars) throughout the plant
Xylem – transports water and
dissolved ions from the root
to the stem and leaves.
Phloem – carries dissolved sugars
from leaves to rest of the plant

9. Xylem Transports water and dissolved minerals
Tracheids: long, thin tube like structures without perforations at the ends
Vessel elements: short, wide tubes perforated at the ends (together form a pipe, called vessel).
Both cells have pits (thin sections) on the walls
Tracheids
Vessel elements

10. Xylem cells Xylem cells are dead!
They are hollow cells and consist only of cell wall

11. Phloem Cells that transport organic materials (sugars)
Phloem cells are ALIVE! (unlike xylem)
However, they lack nucleus and organelles

12. Phloem: transports sugars
Phloem composed of cells called sieve tube members (STM)
Companion cells join sieve tube members, are related, and help to load materials into STM
End walls of STM have large pores called
sieve plates
Companion cells
Sieve tube member
Sieve plates

13. 3. Ground tissue Makes up the bulk of plant organs.
Functions: Metabolism, storage and support.
Root Stem Leaf

14. Plant Organs
Organs: tissues that act together to serve a specific function
Roots
Stems
Leaves
Dermal
Vascular
Ground
Dermal
Vascular
Ground
Dermal
Vascular
Ground

15. Functions of plant organs:
ROOTS: Anchorage, water/nutrient absorption from soil, storage, water/nutrient transport
STEMS: Support, water/nutrient transport
LEAVES: Photosynthesis (food production)

16. ROOTS ROOTS “the hidden half” Functions of roots: Ancorage
Absorption of water & dissolved minerals
Storage (surplus sugars, starch)
Conduction water/nutrients

17. Anatomy of a root
epidermis
cortex
vascular

18. Root Epidermis Outermost, single layer of cells that:
Protects (from diseases)
Absorbs water and nutrients
ROOT HAIRS: tubular extensions
of epidermal cells.
Increase surface area of root,
for better water/nutrient
absorption

19. Root Hairs: water and mineral absorption
increase surface
area for better
absorption

20. Root Cortex
Stores starch, sugars and other substances

21. You’re not a yam, you’re a sweetpotato!
Root Ground tissue
In roots, ground tissue (a.k.a. cortex) provides support, and
often stores sugars and starch
(for example: yams, sweet potato, etc.)
You’re not a yam, you’re a sweetpotato!
Hey!
I yam what I yam, man!
cortex

22. STEMS Above-ground organs (usually) Support leaves and fruits
Conduct water and sugars
throughout plant (xylem and phloem)

23. Stem anatomy Dermal, ground and vascular tissues… epidermis cortex
pith
Vascular
bundles

24. Types of Stems
Monocot stem Dicot stem Root

25. Types of stems
Herbaceous vs Woody stems

26. Tissues of stems Epidermis (Dermal tissue type) Provides protection
Has cuticle (wax) prevents water loss
Trichomes (hairs) for protection, to release scents, oils, etc.

27. Stem Vascular tissue
Vascular bundles – composed of both xylem and phloem
Xylem
Conducts water
Support
Phloem
Conducts food
Vascular
cambium

28. Vascular cambium Occurs in woody stems
Vascular cambium located in the middle of the vascular bundle, between xylem and phloem

29. Vascular tissue: Trees
Vascular tissue is located on the outer layers of the tree.
bark
wood
phloem
Vascular cambium
xylem

30. Vascular tissue forms rings in trees
Annual rings: xylem formed by the vascular cambium during one growing season
One ring = one year

31. History of the tree: annual rings
Dendrochronology : tree time-keeping
1917 & 1945: Tree
Survives two World
Wars
1776: Declaration
of US independence
1969: Man
lands on Moon
1492: Columbus lands in
the Americas
1620: Pilgrims land
in Plymouth, Mass.
1861: Start of
Civil War
1489: Tree is planted
by Native American
1971: Birth Year
of the IDIOT
who cut down
this tree!!!

32. LEAVES: ‘Photosynthetic factories’ of the plant…
Function: Photosynthesis – food
production for the whole plant
Blade: Flat expanded area
Petiole: stalk that connects
leaf blade to stem, and
transports materials
BLADE

33. Leaf Anatomy Leaf anatomy is correlated to photosynthesis:
Carbon dioxide + Water  sugars + oxygen
dermal
ground
vascular
dermal

34. Leaf epidermis Is transparent – so that sun light can go through.
Waxy cuticle protects against drying out

35. Leaf epidermis Stomata open and close, by the guard cells.
Lower epidermis: stomata with guard cells – for gas exchange (CO2, H2O in; O2 out)

36. Leaf vascular tissue VEINS  vascular tissue of leaves.
Veins are composed of xylem (water transport) phloem (food transport)
and bundle sheaths,
cells surrounding the
xylem/phloem for
strength & support

37. Leaf Mesophyll Middle of the leaf (meso-phyll)
Palisade (long columns below epidermis;
have lots chloroplasts for
photosynthesis)
Spongy parenchyma
(spherical cells)
with air spaces around,
(for gas exchange)

38. Plant water transport How can water move from the ground all the way
to the top
of a 100 m
tall redwood
tree?

39. Water transport in plants:
The same way we drink soda
from a straw!
Water’s great
cohesive forces (molecules
sticking to each other)
and adhesive forces
(attaching to walls of xylem cells)

40. Transpiration for water transport in the xylem
Evaporation of water in the leaves (through stomates) generates the ‘sucking force’ that pulls adjacent water molecules up the leaf surface

41. Water transport (cont.)
Like a long chain, water molecules pull each other up the column.
The column goes from roots  leaves.
What’s amazing is that the
water moves up by using the sun’s
evaporative energy…
Plants control transpiration by opening/closing stomata

42. Plant Hormones Chemical compounds produced by plants
Effective at very low concentrations
Five major hormone groups are:
Auxins
Gibberellins
Cytokinins
Abscisic Acid
Ethylene

43. 1. AUXINS Promote cell growth Involved in gravitropism
and phototropism
Control fruit development

44. 2. Gibberellins 3. Cytokinins 4. Abscisic Acid Promote stem elongation
Promote cell division and
organ differentiation
4. Abscisic Acid
Promotes seed dormancy
Causes stomata closing

45. 5. ETHYLENE Gaseous hormone, very simple formula (C2H4)
Ethylene promotes
fruit ripening!
Air Ethylene

46. “One rotten apple spoils the barrel”
Why?
Probably due to ethylene!
Rotten apple producing
lots of ethylene!
Autocatalytic
As a response to injury

47. Avocado ripening…
Place in a paper bag, with a ripe banana!