Plant anatomy & physiology

Plant Anatomy & Physiology
By: Johnny M. Jessup
Agricultural Instructor/FFA Advisor

The Four Basic Parts of Plants
 Leaves
 Stems
 Roots
 Flowers

Leaves
 Functions
 Make food through photosynthesis
 Site of gas exchange
 Respiration
 Photosynthesis
 Store food

Tissues of the Leaf (Epidermis)
 Cuticle
 Waxy substance that
covers the leaves &
stems
 Waterproof layer that
keeps water in plants

 Stomata
 Openings in the
epidermis mainly
located on the
underside of leaves
 Exchange of gases

 Guard Cells
 Two cells located on
each side of stomata
 Open and closes
stomata

Tissues of the Leaf
(Mesophyll Layer)
 Palisade mesophyll
 Primary site of photosynthesis
 Spongy mesophyll
 Contains air & chloroplasts
 Site of photosynthesis and gas exchange

Tissues of the Leaf
 Vascular Bundles
 Called veins
 In spongy mesophyll
 Phloem moves food
from leaf to the rest
of the plant
 Xylem moves water
& minerals up to
leaves from roots

External Parts of the Leaf
 Petiole
 Leaf stalk or part that connects the leaf to
the stem.
 Blade
 The large, flat part of a leaf.
 Midrib
 The large center vein.

Stems
 Functions
 Movement of materials
 Water & minerals from roots to leaves
 Manufactured food from leaves to roots
 Support leaves & reproductive structures
 Food storage

External Stem Structure
 Lenticels
 Breathing pores.
 Bud Scale Scars
 Show where terminal buds have been
located.
 Leaf Scars
 Show where leaves were attached.

External Stem Structure
 Terminal Bud
 Bud on the end of the stem.
 Axillary Lateral Bud
 Bud on the side of the stem.

Internal Stem Structure
 Xylem
 The tissue that transports water & nutrients up
from roots to stems & leaves.
 Phloem
 Tissue that transports food down from leaves to
roots.
 Cambium
 Thin, green, actively growing tissue located
between bark & wood and produces all new stems
cells.

 Bark
 Old, inactive phloem.
 Heartwood
 Old, inactive xylem.
 Sapwood
 New, active xylem.

(Monocots)
 Vascular bundles
contain both xylem
& phloem.
 Examples:
 Grasses
 Corn

Monocot Stems
(Vascular Bundle)

(Dicots)
 Plant stems have
xylem & phloem
separated by the
cambium.
 Example:
 Trees

(Dicots)

Specialized Types of Stems
 Corm
 Underground
 Solid, fleshy, scale
covered
 Examples
 Gladiolus
 Crocus

 Bulb
 Layers of fleshy
scales that overlap
each other
 Underground stem
 Examples
 Tulips
 Lilies
 Onions

 Tubers
 Food Storage Area
 Short, thick
underground stem
 Examples
 Potato
 Caladium

 Crown
 Closely grouped
stems or plantlets
 Just above or
below ground
 Examples
 African violet
 Ferns

 Spurs
 Short stems found
on woody limbs
adapted for
increased fruit
production
 Examples
 Apple
 Pear

 Rhizomes
 Underground stems
that produce roots on
the lower surface
and extend leaves
and flower shoots
above ground
 Examples
 Iris
 Lily of the Valley

 Stolens
 Stem that grows
horizontally above
the soil surface
 Examples
 Strawberries
 Airplane Plant

Roots
 Functions
 Anchor the plant
 Absorb water & minerals
 Store food
 Propagate or reproduce some plants

Different Types of Roots
 Tap Root
 One main root, no
nodes
 Continuation of the
primary root
 Ideal for anchorage
 Penetration is
greater for water
 Storage area for food

 Fibrous Root
 Many finely
branched secondary
roots
 Shallow roots cover
a large area
 More efficient
absorption of water &
minerals
 Roots hold the soil to
prevent erosion

 Aerial Roots
 Clinging air roots
 Short roots that grow
horizontally from the
stems
 Roots that fasten the
plant to a support
 Absorptive air roots
 Absorb moisture from
the air

 Adventitious Roots
 Develop in places
other than nodes
 Form on cuttings &
rhizomes

External Parts of Roots
 Root Cap
 Indicates
growth of
new cells.

External Parts of Roots
 Root Hairs
 Tiny one celled hair-
like extensions of the
epidermal cells
located near the tips
of roots.
 Increase surface
area.
 Absorb water &
minerals.

Internal Parts of Roots
 Much like those of stems with phloem,
cambium and xylem layers.
 Phloem
 The outer layer.
 Carries food down the plant.
 Xylem
 The inner layer.
 Carries water & minerals up to the stem.

Flowers
 Function
 Contain the sexual
organs for the plant.
 Produces fruit, which
protects, nourishes
and carries seeds.
 Attracts insects for
pollination.

Parts of the Flower
 Sepals
 Outer covering of the
flower bud.
 Protects the stamens
and pistils when
flower is in bud
stage.
 Collectively known
as the calyx.

Parts of the Flower
 Petals
 Brightly colored
 Protects stamen &
pistils.
 Attracts pollinating
insects.
 Collectively called
the corolla.

Parts of the Flower (Stamen)
 Male reproductive
part
 Anther
 Produces pollen
 Filament
 Supports the anther

Parts of the Flower (Pistil)
 Female reproductive
part
 Ovary
 Enlarged portion at
base of pistil
 Produces ovules
which develop into
seeds
 Stigma
 Holds the pollen
grains

Parts of the Flower (Pistil)
 Style
 Connects the stigma with the ovary
 Supports the stigma so that it can be
pollinated

Imperfect Flower
 Male or female
reproductive organs
not, but not both.
 Example:
 A male flower has
sepals, petals, and
stamen, but no pistils.
 A female flower has
sepals, petals, and
pistils, but no stamen.

Perfect Flowers
 Contains both male
and female
reproductive
structures.

Incomplete Flowers
 Missing one of the
four major parts of
the flower.
 Stamen
 Pistil
 Sepal
 Petal

Complete Flowers
 Contains male and
female reproductive
organs along with
petals and sepals.

Flowers
 Imperfect flowers are always incomplete
but……..
 Perfect flowers are not always complete
and……..
 Complete flowers are always perfect.

Importance of Flowers
 Important in florist &
nursery businesses.
 Many plants are grown solely
for their flowers.
 Plants have flowers to attract insects for
pollination, but people grow them for
beauty & economic value.

 Johnny M. Jessup, FFA Advisor
 Hobbton High School
Designed By:

Plant anatomy & physiology

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