Science

1. 1
Plant Science
Plant Structures
Instructional Materials Service
Texas A&M University
- 8384 -

2. 2
Plant Structures
 Parts of a Vascular Plant
 Root Structure
 Stem Structure (External)
 Leaf Structure
 Parts of a Complete Flower

3. 3
Plant Cell Anatomy

4. 4
Parts of a Vascular Plant

5. 5
Plant Organs
Plant organs include their roots, stems,
leaves, and reproductive structures. Each
plant organ performs a specialized task in
the life of a plant.
 Roots, stems, and leaves are all vegetative
structures.
 Flowers, seeds, and fruits make up
reproductive structures.

6. 6
Plant Organ Functions
 Roots support the plant and supply it with
water and nutrients.
 Stems connect the root and leaves.
 Leaves capture energy from the sunlight and
use it to make food for the plant.
 Reproductive structures attract pollinators and
produce seeds and fruits.

7. 7
To help prevent soil erosion,
which root system would be
best?
 Fibrous

8. 8
Taproots
 Advantages
 Penetrates
deeper
 Obtain water
from other
levels
 Anchor plant
 Disadvantages
 Difficult to
remove or
harvest
 do not stabilize
well

9. 9
PARTS OF PLANT ROOT

10. 10
Fibrous
 Advantages
 Shallower,
better for
fertilization &
Water
 Stabilize in soil
better
 Disadvantage
 Less drought
resistant
 Tend to get
exposed during
cultivation

11. 11
Primary Roots
 Grow down into the
soil and may branch
repeatedly into
lateral roots
 Taproot is a primary
root

12. 12
Lateral Roots
 Called Secondary roots
 grow horizontally away from the
primary root
 Some grow downward

13. 13
Root Structure
Xylem (water transport)
Meristem
Root Hairs
Epidermis
Cortex
Phloem Tubes
Root Cap
Zone of
Elongation
Zone of
Differentiation

14. 14
The Epidermis
Epidermis
The epidermis is the
outermost layer of cells
surrounding the root.
The cells of the epidermis
are responsible for
absorbing water and
minerals from the soil

15. 15
The Cortex
Cortex
The cortex is a layer
of tissue between the
epidermis and the
vascular tissue.
Cortex cells function in
the movement of
water and in food
storage.

16. 16
Root Hairs
Root Hairs
Root hairs are found
along the main root and
perform much of the
actual work of water and
nutrient absorption.
Most plants produce root
hairs that only live a few
days or a few weeks.
As a plant grows, new
root hairs form.

17. 17
Xylem
Xylem is the
supporting and water
conducting tissue of
vascular plants.
Xylem

18. 18
Phloem
Phloem is the food
conducting tissue of
vascular plants, made up
of sieve tubes and other
cellular material.
Phloem

19. 19
Meristem
Meristem
The meristem is at the
tip of the root and is
responsible for
manufacturing new cells.
This is the area where
cell division and growth
occur.

20. 20
Roots
 The root is the first plant structure to
emerge from a seed during germination.
 Roots are mostly found below the soil
surface and represent about 50% of a
plant’s weight.
 The primary functions of roots are to absorb
water and nutrients from the soil and to
support the plant in an upright position.

21. 21
 Roots distribute the food energy produced
in the leaves to the rapidly growing areas
found at the root tips.
 Some plants use their roots as a
specialized food storage reserve.
 The first root to emerge from a seed is the
primary root, or radicle.
Root Functions

22. 22
 Plant root systems are classified based on
the relative sizes of their primary and
secondary roots.
 Plants such as dandelions, carrots, turnips,
and most trees have a taproot.
 In taproot systems, the primary root thickens
and becomes the dominant root.
Roots (taproot)

23. 23
 In fibrous root systems, the primary and
secondary roots are of similar diameter.
 They remain fairly close to the soil surface.
 Fibrous root systems help to prevent the
erosion of topsoil during heavy rains.
 Plants such as onions, grasses, and corn
have fibrous root systems.
Roots (fibrous)

24. 24
Root Types
Fibrous Roots
Tap Root

25. 25
Stem Characteristics

26. 26
Stems
Stems function as supportive
structures. They hold a plant’s
leaves up toward the sun so
the leaves can capture
energy from sunlight.
Stems transport water and
nutrients from the roots to the
leaves, and food energy from
the leaves to the roots.

27. 27
Leaf Structure
Bladestalk
(Petiole)
Axillary
Bud
Node
Internode Base of Leaf
Midrib
Vein
Expanded
Portion of Blade
(Lamina)

28. 28
Leaf Characteristics

29. 29
Midrib & Veins
Midrib The midrib is the
most prominent,
central vein in a leaf.
Lateral veins are
secondary veins that
branch from the
midrib.
Both midribs and
lateral veins contain
vascular tissue.
Vein

30. 30
Leaf Blade (Lamina)
Leaf Blade (Lamina)
The expanded flat
portion of a leaf is the
leaf blade, or lamina.

31. 31
Petiole (Bladestalk)
Petiole
The petiole attaches
the lamina to the plant
stem.

32. 32
Axillary Bud
Axillary Bud
An axillary bud
exists on the stem
just above the
point where the
leaf petiole
attaches to the
stem.

33. 33
Petal
Sepal
Parts of a Flower
Stigma
Anther
Receptacle
Filament
Pollen Tube
Ovary
Ovule
Embryo Sac
Microphyle
Style
Integuments
Pollen Grains

34. 34
Complete Flowers
Compete flowers have four basic parts:
1. Sepals
2. Petals
3. Stamens
4. Pistil

35. 35
Sepals
Sepals
Sepals are leaf-like
structures that form an
outer ring around the
base of a flower.
Sepals enclose and
protect a flower bud
before it opens.
The complete ring of
sepals is called the
calyx.

36. 36
Petals
Petals
Petals are often the
bright and colored
part of a flower.
Petal colors and
scents attract specific
pollinators.

37. 37
Stamens
Anther The stamen contains
both the filament and
the anther.
The filament is a stalk-
like structure that
holds the anther.
Stamens are the male
reproductive parts of a
flower.
Filament

38. 38
Pistil
Stigma
Style
Ovary
The pistil includes
three parts:
1. Stigma
2. Style
3. Ovary

39. 39
Pistil 1. Stigma
Stigma The stigma is a sticky,
flattened surface that
projects upwards
towards the pollinator.
Birds and insects collect
nectar from previously
visited plants and brush
against the sticky
surface of the stigma.

40. 40
Pistil 2. Style
Style
The style is a
supportive structure
that holds the stigma in
a position to maximize
the chances of
pollination.

41. 41
Pistil 3. Ovary
Ovary
Pollen Tube
Ovule
The ovary is an
enlarged structure
that contains the
female sex cells, or
ovules.
The pollen tube
grows through the
ovary and into an
ovule.

42. 42
Receptacle
The enlarged part of
the pedicel where it
joins the flower is the
receptacle.
Receptacle

43. 43
Pedicel
Pedicel
The pedicel (flower
stalk) supports the
flower.

44. 44
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Acknowledgements
Kristi Falco, Graduate Assistant, Instructional Materials Service,
researched and developed the information used in this
PowerPoint Presentation.
Christine Stetter, Artist, Instructional Materials Service,
developed and illustrated this PowerPoint Presentation..
Keith Zamzow, Curriculum Specialist, Instructional Materials
Service, edited and reviewed this PowerPoint Presentation.
Vickie Marriott, Office Software Associate, Instructional
Materials Service, edited this PowerPoint Presentation.

46. 46
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RESERVED
Reproduction or redistribution of all, or
part, of this presentation without
written permission is prohibited.
Instructional Materials Service
Texas A&M University
2588 TAMUS
College Station, Texas 77843-2588
http://www-ims.tamu.edu
2006