botany

1. Basic Botany, Plant Physiology,
and Environmental Effects on
Plant Growth
The University of Tennessee
Master Gardener Program
Updated January 2002

2. Objectives
 To develop a basic
understanding of:
 Botany
 Plant Physiology
 Environmental Factors that
affect Plant Growth
 To apply this basic
understanding to home
gardening.

3. Topics
 Plant Parts and Functions
 Stems
 Leaves
 Buds
 Roots
 Flowers
 Fruit
 Seed
 Plant Development
 Photosynthesis
 Respiration
 Transpiration
 Environmental Factors
Affecting Plant Growth
 Temperature
 Light
 Water

4. Plant Parts
 Reproductive
 Flower Buds
 Flower
 Fruit
 Seeds
 Plant parts of sexual
reproduction
 Vegetative
 Roots
 Stems
 Leaves
 Leaf Buds
 Often used in asexual
reproduction (vegetative)

5. Principal Parts of a Vascular Plant

6. Stems
 Stems support:
 Buds
 Flowers
 Leaves
 Stems transport:
 Water
 Minerals
 Sugars
 Nodes
 The points where leaves
develop along a stem
 Regions of high cellular
activity
 The distance between nodes
(internode) is affected by:
 Light (etiolation)
 Water
 Nutrients (N and micros)
 Genetics

7. Nodes and Buds
 Many plants develop one
or more buds at the nodes
(axillary buds)
 Axillary buds may grow
into lateral branches
 When pruning a plant it is
very important to make cuts
just above axillary buds:
 Axillary buds grow
 Wound heals quickly
 When making cuttings,
they should be made just
below a node:
 Many plants root more
easily at nodes, some only
at nodes.
 Managing light, water,
nutrients, and genetics are
important to healthy
transplant production!

8. Proper Pruning Cut: Tree

9. Proper Pruning Cut: Cane

10. Plant Cuttings

11. Types of Stems
 Shoot
 A young stem with leaves
present
 Twig
 A stem less than 1 year old
with no leaves present
(dormant)
 Branch
 A stem more than 1 year
old, with lateral buds
 Trunk
 A main stem of a woody
plant
 Trees generally have a single
trunk
 Shrubs often have 2 or more
trunks
 Vines
 A long trailing stem that is
able to support itself by
winding around other plants

12. Types of Stems and Modifications
 Canes
 A stem that lives only a
year or two
 Contain a large amount pith
(soft tissue) in the center
 Stem modifications
 Above-Ground
 Crowns
 Stolons
 Spurs
 Below-Ground
 Bulbs
 Corms
 Rhizomes
 Tubers
 All of these have buds or
leaves present
 Can you think of examples
of these structures?

13. Above-Ground Stem Modifications
Stolons and Crowns Spurs

14. Below-Ground Stem Development
Rhizomes Tubers

15. Below-Ground Stem Development
Corm Bulb

16. Vascular Tissue:
“The Plants Circulatory System”
 Xylem
 Transports water, nutrients, &
minerals from roots to upper
portions of the plant
 Forms the “wood” of woody
plants
 Phloem
 Conducts sugars from leaves to
growing points, fruits, & storage
areas
 Comprises much of the bark of
woody plants
 Cambium
 Cambium is the
meristematic tissue (the site
of cell division and growth)
 It is located between the
xylem and phloem and
produces both tissues
 Other meristematic tissue is
found at the apical bud,
where stem elongation
takes place

17. Arrangements of Vascular Tissue
 “Dicots”
 Vascular tissue form rings
 Woody plants
 “Monocots”
 Vascular tissue arranged in
bundles
 Grasses, Orchids, Lilies
 Lack cambium tissue
between xylem and phloem
 Stems of dicots tend to
grow in diameter, while
stems of monocots tend
not to increase in diameter
 What does knowing about
these tissues reveal to you
about:
 Damage to the bark of a
tree?
 Grafting?

18. Diagram of Vascular Tissue

19. Life Span of a Stem
 We often classify stems by
how long they live:
 Annual
 Produce seed and die within
1 year
 Biennials
 Produce vegetative structures
and food storage organs the
first year
 Reproduction takes place the
second year and the plant
dies
 When stressed, biennials can
go through the entire process
in 1 year (bolting)
 Perennials
 Live 3 or more years
 Usually produce flowers and
seeds every year
 Herbaceous Perennial
 Shoots which die back to the
ground every year
 “Biennial Perennials”

20. Leaves
 Leaves:
 Are attached to the stem by
petioles
 Consist of:
 Blade
 Midrib
 Smaller Veins
 Function
 To manufacture sugars in a
process called photosynthesis
 Functions
 Petiole:
 Expands the leaf area and
orients the leaf
 Blade:
 Provides a large area for the
efficient absorption of light
 Midrib and Veins:
 Conducts water, sugar, and
other compounds throughout
the leaf

21. Type of Leaves

22. Outer Leaf Structure
 Epidermis
 Outer protective layer
 Trichomes
 Extensions of epidermis that
make leaves feel like velvet
 Cuticle
 Waxy layer (cutin) in some plants
that protects plants from:
 Dehydration
 Penetration by some diseases
 Guard Cells
 Special epidermal cells that are
capable of enlarging and
contracting
 Stomates
 Openings that develop between
enlarged guard cells
 Usually on the underneath side of
the leaf
 Regulate the passage of water,
oxygen, and carbon dioxide in
and out of the leaf

23. Inner Leaf Structure
 Mesophyll
 Where photosynthesis occurs
 Is comprised of 2 layers
 Palisade cells
 Parenchyma layer
 Palisade Cells
 Dense upper layers of the leaf
 Parenchyma Layer
 Lower spongy area with
considerable air space
 Chloroplasts
 Actual site of photosynthesis
 Found in the palisade cells and
the parenchyma layer
 Some plants vary leaf
thickness with environmental
conditions
 Special Leaves
 Bracts
 Tendrils
 Cotyledons

24. Structure of a Leaf Blade

25. Bracts

26. Tendrils

27. Cotyledons

28. Leaf Shape and Plant Identification
 Leaves are one of the primary
characteristics in plant
identification
 Veining
 “Structure”
 Shape
 Margins
 Arrangement
 Leaf Veins
 Veins are the continuation of
vascular tissue from the stem,
through the petiole
 Veining Patterns
 Parallel
 Run parallel with length of
the leaf
 Are connected by minute,
straight veins
 Prominent in monocots
 Net
 Pinnate
 Palmate
 Prominent in dicots

29. Types of Leaf Veins

30. Leaf “Structure”, Shape, and Margins
 “Structure”
 Simple
 Compound
 Palmate
 Pinnate
 Double Pinnate
 Shape
 Blade
 Apex
 Base
 Margins
 Entire
 Serrate
 Crenate
 Dentate
 Ciliate
 Lacerate
 Sinuate
 Incised
 Lobed
 Cleft

31. Simple and Compound Leaf Types

32. Leaf Shapes

33. Common Leaf Shapes
 Acuminate: Tapering to a long, narrow point.
 Acute: Ending in an acute angle, with a
sharp but, not acuminate point.
 Obtuse: Tapering to a rounded edge.
 Sagittate: Arrowhead-shaped, with two
pointed lower lobes.
 Truncate: Having a relatively square end.

34. Leaf Margins

35. Common Leaf Margins
 Entire: A smooth edge with no teeth or notches.
 Serrate: Having small, sharp teeth pointed toward the apex.
 Dentate: Having teeth ending in an acute angle, pointing
outward.
 Crenate: Having rounded teeth.
 Sinuate: Having a pronounced sinus or wavy margin.
 Incised: Margin cut into sharp, deep, irregular teeth or incisions.
 Lobed: Incisions extend less than halfway to the midrib.
 Cleft: Incisions extend more than halfway to the midrib.

36. Leaf Arrangement
 Leaf arrangement along the
stem
 Rosulate
 Basal leaves form a rosette
 Short internodes
 Opposite
 Two leaves exactly opposite
 Alternate
 Steps or spiraled
 Whorled
 Circles of three or more leaves
 Uses of Leaves
 Food
 Humans
 Animals
 Wild
 Livestock
 Ornamental
 Color
 Shape
 Soil Amendments

37. Leaf Arrangement

38. Leaf Arrangement (cont.)

39. Buds
 Buds are undeveloped
shoots from which leaf or
flower parts arise
 Bud Scales
 Small, leathery, modified
leaves that cover buds
 Bud Scale Scars
 Scars formed when the bud
scales are removed
 Used in plant identification
 Types of Buds
 Terminal – dominant
 Auxin
 Lateral or axillary
 Adventitious
 May originate from
internodes, leaves, or callus
tissue of stems or roots
 Chilling Requirements
 Bud Use

40. Roots
 Principal Functions
 Obvious
 Absorb Water
 Nutrient Uptake
 Also
 Transport water and nutrients
to the stem
 Anchor / Support
 Serve as storage organs
 Propagation
 Parts or Zones of Growth
 Merisematic Zone
 Where new cells are formed
 Root Cap – protects root tip
 Zone of Elongation
 Cells increase in size and
push root
 Zone of Maturation
 Cells differentiate
 Root hairs form – short-lived,
small roots - absorption

41. Root Structure

42. Root Systems
 Two types of Root
Systems
 Tap
 Develops a main tap root
with various amounts of
lateral rooting
 Fibrous
 Develops small roots that
spread out in a mat-like
growth
 Uses
 Food
 Humans
 Fresh
 Processed
 Animals ?
 Medicinal
 Dried
 Fresh ?

43. Flowers
 Flowers are generally the
showiest part of the plant, but
they also serve a purpose
 Sexual Reproduction
 Color and / or
 Odor
attracts pollinators (insects)
 Flowers are least influenced by
environmental conditions;
therefore they are important in
plant identification.

44. Flower Parts
 Sepals
 Small, green leaf-like
structures at the base of the
flower that protect the
flower bud
 Collectively – Calyx
 Petals
 Colored and aromatic part
 Collectively – Corolla
 The number of sepals and
/ or petals helps identify
the family or genera
 Dicots generally have
multiples of 4 or 5
 Monocots generally have
multiples of 3
 Example
 Members of the “Rose”
family have 5 petals and
sepals.

45. Reproductive Flower Parts
 Female
 Pistil (shaped like a
bowling pin)
 Stigma (top)
 Style (middle)
 Ovary (bottom)
 Placenta
 Ovules – develop into seed
after pollination
 Male
 Stamen (flowers often have
a cluster of stamens around
the pistil)
 Anther (pollen sac)
 Pollen is produced by the
anther
 Filament (“stem”) supports
the anther

46. Structure of a Generalized Flower

47. Types of Flowers
 Complete – all four parts
 Incomplete – lacks one
part
 Perfect – contains both
function pistils and
stamens
 Imperfect – lacks a
functioning pistil or
stamen
 Self-pollination
 Cross-pollination
 Monoecious – both male
and female flowers on one
plant
 Dioecious – contains only
male or female flowers on
a single plant

48. Common Flower Inflorescences

49. Common Flower Inflorescences (cont.)

50. What Is a Fruit?
 Something you eat for
desert (not with the entrée)
 Botanically, fruit is a
ripened ovary
 Mature ovules (seeds)
 Ovary wall (flesh)
 Examples
 Tomatoes, cucumber,
eggplant, beans
 Types of fruit
 Simple
 Single flower – tomato
 Aggregate (compound)
 Single flower with many
ovaries – strawberry
 Multiple
 Tight cluster of many flowers
– pineapple

51. Seed Structure
 Three Main Parts
 Embryo – partially developed
plant in a dormant state
 Radicle – embryonic stem
 Hypocotyl – stem
 Cotyledons – seed leaves
 Plumule – underdeveloped stem
and leaves
 Endosperm – food source
 Seed Coat – protection from
insects, diseases, and germination
 Seed Growth
 Germination – resumption
of seed growth
 Moisture
 Oxygen
 Favorable temperature
 Light (sometimes)

52. Primary Parts of Common Seeds

53. Seed Germination and Storage
 Most seeds require time
after maturity before they
will germinate.
 Others will require:
 Stratification
 Scarification
 Soaking
 Time, time, time!
 Storage
 Seeds are living things!
 They “live” longer when
maintained in a cool and
dry environment.
 Keep seed packets air tight
(except beans ?)
 Store in a refrigerator or
freezer

54. Plant Growth and Development
 Three major processes
 Photosynthesis
 Respiration
 Transpiration

55. Photosynthesis
 Photosynthesis – “to put
together with light”
 Requirements:
 Light
 Carbon Dioxide
 Water
 Suitable Temperature
 Process – very complicated,
but a simple description
 Carbon dioxide and water are
combined using solar energy
 Simple sugars (glucose is
formed and oxygen is give off
(in the chloroplasts)
 Simple sugars are then
converted into more complex
sugars and starches; and stored
 All green tissue is capable of
photosynthesis, but most takes
place in the leaves
 What limits photosynthesis?

56. Respiration and Transpiration
 Respiration is the
“opposite” of
photosynthesis
 Carbohydrates are broken
down and the energy
released is used for life
processes
 As night-time
temperatures increase,
respiration increases
 Transpiration is the process
by which plants loose water
vapor
 90% of the water entering a
plant is transpired
 Water movement is important
in moving nutrients, minerals,
sugars, and other compounds;
as well as maintaining turgor
pressure and evaporative
cooling

57. How a Plant Grows

58. Photosynthesis vs. Respiration
 Photosynthesis
 Produces sugars
 Stores energy
 Releases oxygen
 Uses water
 Uses carbon dioxide
 Occurs in sunlight
 Occurs in chloroplast
 Respiration
 Uses sugars for energy
 Release energy
 Uses oxygen
 Produces water
 Produces carbon dioxide
 Occurs in dark and light
 Occurs in all cells

59. Environmental Factors
 Primary environmental
influencing plant growth
 Temperature
 Light
 Water

60. Temperature
 Temperature is the main
environmental factor affecting
plant growth
 Germination
 Cool-Season vs. Warm-Season
 Hardiness
 Cold – Desiccation
 Heat
 Growth and fruit set
 Temperature influences quality!

61. Temperature and Germination

62. Light
 Three principal
characteristics:
 Quantity
 Intensity or brightness
 Phototropism
 Quality
 Color or wavelengths
 Red and blue light are most
important
 Green is reflected by the
plant
 Duration
 Photoperiod – amount of time
a plant is exposed
 Short-Day
 Flower during long nights
 Mums and poinsettia
 Day-Neutral
 Not influenced by day
length
 Ever-bearing strawberries
 Long-Day
 Flower during short nights
 Most summer plants

63. Light Management
Not Enough! Too Much!

64. Water
 Water comprises most of
all living things!
 The plant is no different!
 Main component of
protoplasm – the living part
of the cell
 Water Acquisition
 Root hairs
 Vascular tissue
 Stomates
 Quality
 Low in salts
 Temperature
 Quantity
 Too much
 Diseases
 Too little
 Wilting
 Special structures
 Leaves

65. Water Management
Too Much! Not Enough!

66. Questions?