Transcript Parts of a Flower

Plant Science
Plant Structures
Instructional Materials Service
Texas A&M University
- 8384 -
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Plant Structures
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Parts of a Vascular Plant
Root Structure
Stem Structure (External)
Leaf Structure
Parts of a Complete Flower
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Parts of a Vascular Plant
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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.
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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.
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Root Structure
Zone of
Differentiation
Epidermis
Cortex
Root Hairs
Phloem Tubes
Zone of
Elongation
Xylem (water transport)
Root Cap
Meristem
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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
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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.
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Root Hairs
Root hairs are found
along the main root and
perform much of the
actual work of water and
nutrient absorption.
Root Hairs
Most plants produce root
hairs that only live a few
days or a few weeks.
As a plant grows, new
root hairs form.
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Xylem
Xylem is the
supporting and water
conducting tissue of
vascular plants.
Xylem
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Phloem
Phloem
Phloem is the food
conducting tissue of
vascular plants, made up
of sieve tubes and other
cellular material.
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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.
Meristem
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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.
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Root Functions
• 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.
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Roots (taproot)
• 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.
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Roots (fibrous)
• 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.
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Root Types
Tap Root
Fibrous Roots
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Stem Structure (External)
Terminal Bud
Growing Point
Young Leaf
Axillary Bud
Nodes
Petiole
Internode
Abscission Layer
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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.
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Leaf Structure
Vein
Midrib
Expanded
Portion of Blade
(Lamina)
Axillary
Bud
Node
Bladestalk
(Petiole)
Internode
Base of Leaf
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Midrib & Veins
Vein
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.
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Leaf Blade (Lamina)
Leaf Blade (Lamina)
The expanded flat
portion of a leaf is the
leaf blade, or lamina.
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Petiole (Bladestalk)
The petiole attaches
the lamina to the plant
stem.
Petiole
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Axillary Bud
Axillary Bud
An axillary bud
exists on the stem
just above the
point where the
leaf petiole
attaches to the
stem.
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Parts of a Flower
Pollen Grains
Stigma
Filament
Style
Anther
Petal
Pollen Tube
Ovule
Embryo Sac
Microphyle
Ovary
Sepal
Integuments
Receptacle
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Complete Flowers
Compete flowers have four basic parts:
1. Sepals
2. Petals
3. Stamens
4. Pistil
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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.
Sepals
The complete ring of
sepals is called the
calyx.
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Petals
Petals are often the
bright and colored
part of a flower.
Petal colors and
scents attract specific
pollinators.
Petals
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Stamens
Anther
Filament
The stamen contains
both the filament and
the anther.
The filament is a stalklike structure that
holds the anther.
Stamens are the male
reproductive parts of a
flower.
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Pistil
Stigma
The pistil includes
three parts:
1. Stigma
2. Style
3. Ovary
Style
Ovary
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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.
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Pistil 2. Style
The style is a
supportive structure
that holds the stigma in
a position to maximize
the chances of
pollination.
Style
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Pistil 3. Ovary
The ovary is an
enlarged structure
that contains the
female sex cells, or
ovules.
Pollen Tube
Ovule
Ovary
The pollen tube
grows through the
ovary and into an
ovule.
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Receptacle
The enlarged part of
the pedicel where it
joins the flower is the
receptacle.
Receptacle
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Pedicel
The pedicel (flower
stalk) supports the
flower.
Pedicel
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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.
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ALL RIGHTS 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
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